omniomni/omni-engineering huggingface dataset:
Arcjet rocket. An arcjet rocket or arcjet thruster is a form of electrically powered spacecraft propulsion, in which an electrical discharge (arc) is created in a flow of propellant (typically hydrazine or ammonia). This imparts additional energy to the propellant, so that one can extract more work out of each kilogram of propellant, at the expense of increased power consumption and (usually) higher cost. Also, the thrust levels available from typically used arcjet engines are very low compared with chemical engines.

When the energy is available, arcjets are well suited to keeping stations in orbit and can replace monopropellant rockets.

Aerojet MR-510 series arcjet engines are currently used on Lockheed Martin A2100 satellites using hydrazine as a propellant, providing over 585 s average specific impulse at 2 kW.

In Germany, researchers at the University of Stuttgart's Institute of Space Aviation Systems have been working with arcjets for years and have developed various hydrogen-powered arcjet engines capable of power outputs from 1 to 100 kW. The heated hydrogen reaches exit speeds of . An arcjet-propelled test satellite by the name of Baden-Württemberg 1 (BW1) was scheduled to go to the Moon by 2010. No such launch has yet occurred. Baden-Württemberg 1 would have used polytetrafluoroethylene (PTFE) propellant.

References

Further reading
 Lichtbogenantriebe für Weltraumaufgaben (Arcjet propulsion systems for space applications), Prof. Monika Auweter-Kurtz, B.G. Teubner Stuttgart 1992 Institute of Space Systems at the University of Stuttgart
 Arcjet (Lichtbogentriebwerk)

External links
 Aerojet Rocketdyne - Arcjet thruster vendor

Rocket propulsion
PDP-7. The PDP-7 is an 18-bit minicomputer produced by Digital Equipment Corporation as part of the PDP series. Introduced in 1964, shipped since 1965, it was the first to use their Flip-Chip technology. With a cost of , it was cheap but powerful by the standards of the time. The PDP-7 is the third of Digital's 18-bit machines, with essentially the same instruction set architecture as the PDP-4 and the PDP-9.

Hardware
The PDP-7 was the first wire-wrapped PDP computer.  The computer has a memory cycle time of  and an add time of . Input/output (I/O) includes a keyboard, printer, punched tape and dual transport DECtape drives (type 555). The standard core memory capacity is   but expandable up to  

The PDP-7 weighs about .

Software
DECsys, the first operating system for DEC's 18-bit computer family (and DEC's first operating system for a computer smaller than its 36-bit timesharing systems), was introduced in 1965. It provides an interactive, single user, program development environment for Fortran and assembly language programs.

In 1969, Ken Thompson wrote the first UNIX system, then named Unics as a pun on Multics despite only using two design elements from Multics, in assembly language on a PDP-7, as the operating system for Space Travel, a game which requires graphics to depict the motion of the planets. A PDP-7 was also the development system used during the development of MUMPS at MGH in Boston a few years earlier.

Sales
The PDP-7  was described as "highly successful." A combined total of 120 of the PDP-7 and PDP-7A were sold. A DEC publication states that the first units shipped to customers in November 1964.

Eleven systems were shipped to the UK.

Restorations
At least four PDP-7s were confirmed to still exist as of 2011 and a fifth was discovered in 2017.

A PDP-7A (serial number 115) was under restoration in Oslo, Norway; a second PDP-7A (serial number 113) previously located at the University of Oregon in its Nuclear Physics laboratory is now at the Living Computer Museum in Seattle, Washington and is completely restored to running condition after being disassembled for transport; Another PDP-7 (serial number 47) is known to be in the collection of Max Burnet near Sydney, Australia, a fourth PDP-7 (serial number 33) is in storage at the Computer History Museum  in Mountain View, California  and a fifth PDP-7 (serial number 129) belonging to Fred Yerian is also located at the Museum, and has been demonstrated running Unix version 0 and compiling a B program.

References

External links
 Information about the PDP-7 and PDP-7/A, including some manuals and a customer list covering 99 of the systems shipped, Digital Equipment Corporation PDP-7.
 

DEC minicomputers
Transistorized computers
18-bit computers
Computer-related introductions in 1965
Products introduced in 1965
Broadband Integrated Services Digital Network. In the 1980s, the telecommunications industry expected that digital services would follow much the same pattern as voice services did on the public switched telephone network, and conceived an end-to-end circuit switched service, known as Broadband Integrated Services Digital Network (B-ISDN).

History
Before B-ISDN, the original ISDN attempted to substitute the analog telephone system with a digital system which was appropriate for both voice and non-voice traffic. Obtaining worldwide agreement on the basic rate interface standard was expected to lead to a large user demand for ISDN equipment, hence leading to mass production and inexpensive ISDN chips. However, the standardization process took years while computer network technology moved rapidly. Once the ISDN standard was finally agreed upon and products were available, it was already obsolete. For home use the largest demand for new services was video and voice transfer, but the ISDN basic rate lacks the necessary channel capacity.

This led to introduction of B-ISDN, by adding the word broadband. Although the term had a meaning in physics and engineering (similar to wideband), the CCITT defined it as: "Qualifying a service or system requiring transmission channels capable of supporting rates greater than the primary rate" referring to the primary rate which ranged from about 1.5 to 2 Mbit/s. Services envisioned included video telephone and video conferencing. Technical papers were published in early 1988. Standards were issued by the Comité Consultatif International Téléphonique et Télégraphique (CCITT, now known as ITU-T), and called "Recommendations". They included G.707 to G.709, and I.121 which defined the principal aspects of B-ISDN, with many others following through the 1990s.

The designated technology for B-ISDN was Asynchronous Transfer Mode (ATM), which was intended to carry both synchronous voice and asynchronous data services on the same transport. The B-ISDN vision has been overtaken by other disruptive technologies used in the Internet. The ATM technology survived as a low-level layer in most digital subscriber line (DSL) technologies, and as a payload type in some wireless technologies such as WiMAX. The term "broadband" became a marketing term for any digital Internet access service.

See also
 Broadband networks
 Dynamic synchronous transfer mode, a revival of circuit switching technology for broadband traffic

References

Further reading
 

ITU-T recommendations
Integrated Services Digital Network
Particle (disambiguation). A particle in the physical sciences is a small localized object to which physical properties can be ascribed.

Particle may also refer to:

Science

 Particle (ecology), in marine and freshwater ecology, a small object
 Colloidal particle, part of a one-phase system of two or more components where the particles aren't individually visible
 Particle, the solid or liquid particles in an aerosol
 Granular material
 Particulates, in the areas of atmospheric physics and air pollution
 Nanoparticle, an object between 1 and 100 nanometers that behaves as a whole
 Point particle, or point mass, an idealization of an object with finite mass but of zero size
 A particle of a medium in continuum mechanics, meaning an infinitesimal portion of it.
 Self-propelled particles, a concept used in statistical physics to model swarms
 Subatomic particle:
 Elementary particle, or fundamental particle, a particle of which other particles are composed
 Particle physics, the study of subatomic particles
 See list of particles for more uses
 Suspended solids, in a liquid

Arts, entertainment, and media
 Particle (band), a 2000 jam band from Los Angeles, California
 Particle (film), a 2012 Turkish film
 Particles (film), a 2019 French film
 "Particles" (song), a 2021 single by Jessica Simpson

Computing
 Particle, a US HTML5 web app company acquired by Apple in 2012
 Particle system, in computer graphics, a technique to simulate certain fuzzy phenomena

Other uses
 Grammatical particle, a function word

See also 
Particulate (disambiguation)
 Particle size (disambiguation)
Standard electrode potential (data page). The data below tabulates standard electrode potentials (E°), in volts relative to the standard hydrogen electrode (SHE), at:
 Temperature ;
 Effective concentration (activity) 1 mol/L for each aqueous or amalgamated (mercury-alloyed) species;
 Unit activity for each solvent and pure solid or liquid species; and
 Absolute partial pressure  for each gaseous reagent — the convention in most literature data but not the current standard state (100 kPa).
Variations from these ideal conditions affect measured voltage via the Nernst equation.

Electrode potentials of successive elementary half-reactions cannot be directly added.  However, the corresponding Gibbs free energy changes (∆G°) must satisfy
,
where  electrons are transferred, and the Faraday constant  is the conversion factor describing Coulombs transferred per mole electrons.  Those Gibbs free energy changes can be added.

For example, from , the energy to form one neutral atom of Fe(s) from one Fe ion and two electrons is  or 84 907 J/(mol ). That value is also the standard formation energy (∆Gf°) for an Fe ion, since  and Fe(s) both have zero formation energy.

Data from different sources may cause table inconsistencies. For example:  From additivity of Gibbs energies, one must have   But that equation does not hold exactly with the cited values.



Table of standard electrode potentials

Legend: (s) – solid; (l) – liquid; (g) – gas; (aq) – aqueous (default for all charged species); (Hg) – amalgam; bold – water electrolysis equations.

See also 
 Galvanic series lists electrode potentials in saltwater
 Standard apparent reduction potentials in biochemistry at pH 7
 Reactivity series#Comparison with standard electrode potentials

Notes

References

External links
 
 
 
 http://www.jesuitnola.org/upload/clark/Refs/red_pot.htm 
 https://web.archive.org/web/20150924015049/http://www.fptl.ru/biblioteka/spravo4niki/handbook-of-Chemistry-and-Physics.pdf
 http://hyperphysics.phy-astr.gsu.edu/Hbase/tables/electpot.html#c1

Electrochemistry
Electrochemical potentials
Chemistry-related lists
OS/390. OS/390 is an IBM operating system for the System/390 IBM mainframe computers.

Overview
OS/390 was introduced in late 1995 in an effort to simplify the packaging and ordering for the key, entitled elements needed to complete a fully functional Multiple Virtual Storage (MVS) operating system package.  These elements included, but were not limited to:

Data Facility Storage Management Subsystem Data Facility Product (DFP)Provides access methods to enable I/O to, e.g., Direct access storage device subsystems, printers, tape; provides utilities and program management
Job Entry Subsystem (JES)Provides the ability to submit batch work and manage print
IBM Communications ServerProvides Virtual Telecommunications Access Method (VTAM) and TCP/IP communications protocols

An additional benefit of the OS/390 packaging concept was to improve reliability, availability and serviceability (RAS) for the operating system, as the number of different combinations of elements that a customer could order and run was drastically reduced.  This reduced the overall time required for customers to test and deploy the operating system in their environments, as well as reducing the number of customer-reported problems, errors (Authorized Program Analysis Reports and Program temporary fixes) arising from the variances in element levels.

In December 2001 IBM extended OS/390 to include support for 64-bit zSeries processors and added various other improvements, and the result is now named z/OS. IBM ended support for the older OS/390-branded versions in late 2004.

See also
 OS/360
 MVS
 z/OS
 z/TPF
 z/VM
 z/VSE
 Linux on IBM Z

References 

IBM mainframe operating systems
IBM ESA/390 operating systems
1995 software
Dyson's eternal intelligence. Dyson's eternal intelligence (the Dyson Scenario) is a hypothetical concept, proposed by Freeman Dyson in 1979, by which an immortal society of intelligent beings in an open universe may escape the prospect of the heat death of the universe by performing an infinite number of computations (as defined below) though expending only a finite amount of energy.

Bremermann's limit can be invoked to deduce a lower bound on the amount of time required to distinguish two discrete energy levels of a quantum system using a quantum measurement. One can interpret this measurement as a computation on 1 bit for this system; however, Bremermann's limit is difficult to interpret physically, since there exist quantum Hamiltonians for which this interpretation would give arbitrarily fast computation speeds at arbitrarily low energy. Following this interpretation, the upper bound on the number of such measurements that can be performed grows over time. Assuming that the energy in the quantum system on which the measurement is performed is lost (while ignoring energy that is lost due to the measurement apparatus itself), the energy available from the mechanism suggested below slows logarithmically, but never stops.

The intelligent beings would begin by storing a finite amount of energy. They then use half (or any fraction) of this energy to power their computation. When the energy is used up, they would enter a state of zero-energy-consumption until the universe cooled. Once the universe had cooled sufficiently, half of the remaining half (one quarter of the original energy) of the intelligent beings' fuel reserves would once again be released, powering a brief period of computation once more. This would continue, with smaller and smaller amounts of energy being released. As the universe cooled, the computations would be slower and slower, but there would still be an infinite number of them.

In 1998, it was discovered that the expansion of the universe appears to be accelerating rather than decelerating due to a positive cosmological constant, implying that any two regions of the universe will eventually become permanently separated from one another. Dyson noted that "in an accelerated universe everything is different". However, even if the cosmological constant is , the matter density in an FLRW universe would converge to  at rate , suggesting that the stored energy would become unavailable even if it is not used.

Legacy
Frank J. Tipler has cited Dyson's writings, and specifically his writings on the  eternal intelligence, as a major influence on his own highly controversial Omega Point theory.
Tipler's theory differs from Dyson's theory on several key points, most notable of which is that Dyson's eternal intelligence presupposes an open universe while Tipler's Omega Point presupposes a closed/contracting universe.  Both theories will be invalidated if the observed universal  expansion continues to accelerate.

See also

References

Physical cosmology
Freeman Dyson
Clustering. Clustering can refer to the following:

In computing:
Computer cluster, the technique of linking many computers together to act like a single computer
Data cluster, an allocation of contiguous storage in databases and file systems
Cluster analysis, the statistical task of grouping a set of objects in such a way that objects in the same group are placed closer together (such as the k-means clustering)
In hash tables, the mapping of keys to nearby slots

In economics:
Business cluster, a geographic concentration of interconnected businesses, suppliers, and associated institutions in a particular field

In graph theory:
The formation of clusters of linked nodes in a network, measured by the clustering coefficient

See also
Cluster (disambiguation)

de:Clustering
Open system (computing). Open systems are computer systems that provide some combination of interoperability, portability, and open software standards. (It can also refer to specific installations that are configured to allow unrestricted access by people and/or other computers; this article does not discuss that meaning).

The term was popularized in the early 1980s, mainly to describe systems based on Unix, especially in contrast to the more entrenched mainframes and minicomputers in use at that time. Unlike older legacy systems, the newer generation of Unix systems featured standardized programming interfaces and peripheral interconnects; third party development of hardware and software was encouraged, a significant departure from the norm of the time, which saw companies such as Amdahl and Hitachi going to court for the right to sell systems and peripherals that were compatible with IBM's mainframes.

The definition of "open system" can be said to have become more formalized in the 1990s with the emergence of independently administered software standards such as The Open Group's Single UNIX Specification.

Although computer users today are used to a high degree of both hardware and software interoperability, in the 20th century the open systems concept could be promoted by Unix vendors as a significant differentiator. IBM and other companies resisted the trend for decades, exemplified by a now-famous warning in 1991 by an IBM account executive that one should be "careful about getting locked into open systems".

However, in the first part of the 21st century many of these same legacy system vendors, particularly IBM and Hewlett-Packard, began to adopt Linux as part of their overall sales strategy, with "open source" marketed as trumping "open system".  Consequently, an IBM mainframe with Linux on IBM Z is marketed as being more of an open system than commodity computers using closed-source Microsoft Windows—or even those using Unix, despite its open systems heritage. In response, more companies are opening the source code to their products, with a notable example being Sun Microsystems and their creation of the OpenOffice.org and OpenSolaris projects, based on their formerly closed-source StarOffice and Solaris software products.

See also
 Open API
 Open format
 Open mainframe
 Open System Environment Reference Model
 Unix wars

References

Computer systems
History of computing
 
Unix history
SVS. SVS may refer to:

Technology
 Advanced Space Vision System, a computer vision system for the ISS
 OS/VS2 (SVS), a precursor of MVS
 ScanScope Virtual Slide, a medical image file format (".svs" suffix)
 Software Virtualization Solution, by Symantec
 Supply Voltage Supervisor, an electronic protective device
 Surround-view system, assisted driving system with multiple cameras
 Synthetic vision system for aircraft

Organizations and companies
 Second Viennese School
 Society for Vascular Surgery
 Sudbury Valley School
 State Veterinary Service, UK
 Saint Vladimir's Orthodox Theological Seminary, Crestwood, NY, US
 Svenska Vitterhetssamfundet, Swedish publisher

Transport
 Seven Sisters station, London, England, National Rail station code
 Stevens Village Airport, IATA code

Other uses
 Standard VIE Settings, of SubSpace video game
 Specific Area Message Encoding, US emergency weather event code
 S. V. Sahasranamam, Indian actor
 Schwartz Value Survey, a personality test
Microware. Microware Systems Corporation was an American software company based in Clive, Iowa, that produced the OS-9 real-time operating system.

Microware Systems Corporation existed as a separate entity from 1977 until September 2001, when it was bought by RadiSys Corp., and became a division of that company. The rights to Microware OS-9 and related software were purchased by a group of distributors on 1 March 2013. The new owner was Microware LP. Microware initially produced a version of BASIC and a real-time kernel for the Motorola 6800 processor, and was asked by Motorola to develop what turned into BASIC09 for the then-new Motorola 6809 processor. Having written BASIC09, they decided it needed an operating system underlying it, and they created the first version of OS-9.

OS-9 was ported to the 68000 family of processors and, after being rewritten mostly in C, to the Intel 80x86, PowerPC, ARM, MIPS, and some of the Hitachi SuperH (SH) series processors. Initially, in the days of the SS-50 bus and SS-50C bus systems such as SWTPC, Gimix, and Smoke Signal Broadcasting, OS-9 was used more as a general purpose microcomputer operating system and had a large, active hobbyist-user population. OS-9 was also popular with industrial and embedded-system users. This was especially true when OS-9 was available for popular 6809-based computers such as the FM-7, FM-77, and the Tandy TRS-80 Color Computer and its near-clone, the Dragon. Over time, Microware concentrated on industrial customers and neglected the hobbyist base that was porting a great many Unix packages and utilities to OS-9.

Microware products 
 RT68 – the original product for the 6800
 OS-9 and OS-9000 – real-time operating systems for a wide range of embedded CPU architectures.
 CD-RTOS – the operating system used in the Philips CD-i players, which was a special version of OS-9/68K v2.4.
 DAVID – the Digital Audio Video Interactive Decoder platform for digital TV.
 Ariel – a micro OS based on an OS Microware acquired (MTOS-UX by IPI).
 Color Computer 3 BASIC ROM extensions to support 80-column text and new graphics modes not in the CoCo 1 and 2's Extended Color BASIC ROM

External links
 

TRS-80 Color Computer
Defunct software companies of the United States
LCF. LCF may refer to:

Organisations
 Canadian Football League (Ligue canadienne de football)
 Lawyers' Christian Fellowship
 London College of Fashion

Science and technology
 Low-cycle fatigue, plastic deformation and low cycle
 LCF notation, for cubic Hamiltonian graphs
 Logic of Computable Functions, a deductive system for computable functions, 1969 formalism by Dana Scott
 Logic for Computable Functions, an interactive automated theorem prover, 1973 formalism by Robin Milner
 Landing Craft, Flak, a World war 2 Landing craft (BPC)

Transportation and military
 Low cab forward, a body style of truck
 Boeing 747 Large Cargo Freighter
 Launch control facility (disambiguation)
 De Zeven Provinciën-class frigate (Luchtverdedigings- en commandofregat, air defense and command frigate)
 Ford LCF, a medium-duty cab-over truck
 Chevrolet LCF (disambiguation), a line of commercial cab-over trucks

Other uses
 La Cañada Flintridge, California, a city in the US
 LCF, a signature in the movie The Ninth Gate
DNS (disambiguation). DNS is the Domain Name System, a network system used to translate names into IP addresses.

DNS may also refer to:

Science and technology
 Deviated nasal septum, a displaced part of the nose
 3,5-Dinitrosalicylic acid, an aromatic compound
 Dinalbuphine sebacate, an analgesic
 Direct numerical simulation, a simulation method in computational fluid dynamics
 Dragon NaturallySpeaking, speech recognition software
 "Do not stuff", the omitting of a component on a printed circuit board

Other uses
 Doctor of Nursing Science, an academic research degree
 Det Nødvendige Seminarium, a teacher training college in Denmark
  (Democratic People's Alliance), a political party in Bosnia and Herzegovina
 Dinas Powys railway station (station code), Wales
 Distressed non-swimmer, a swimming victim type
 Did not start, in the glossary of motorsport terms, also used in other sports
 DNS (retail company), an electronics retailer in Russia

See also
 Didcot, Newbury and Southampton Railway (DN&SR), an English railway 1891–1923