omniomni/omni-engineering huggingface dataset:
DDC. DDC may stand for:

Computing
Distributed Disaggregated Chassis, an open networking design for a router chassis submitted by AT&T to the Open Compute Project. 
Digital distribution copy
Digital down converter, a method in digital signal processing
Display Data Channel, a communication protocol between a graphics card and a monitor defined by VESA

Other
Dansk Datamatik Center, a Danish software research and development centre of the 1980s
DDC-I, a Danish and American company created from the work of the above
Deep Dickollective or D/DC
 Defense Documentation Center for Scientific and Technical Information (United States; until 1963: ASTIA Armed Services Technical Information Agency, from 1979: DTIC Defense Technical Information Center)
Detroit Diesel Corporation
Dewey Decimal Classification
Dideoxycytidine or ddC or zalcitabine
Direct digital control, reading and steering of HVAC devices
District Development Council
Dodge City Regional Airport's IATA code
DOPA decarboxylase or Aromatic-L-amino-acid decarboxylase
Double disc court
Dzongkha Development Commission
United States District Court for the District of Columbia
Dairy Development Corporation of Nepal
District Development Committee (in Nepal)
Double Dealing Character, the fourteenth mainline entry in the Touhou Project video game series.
Student design competition. A student design competition is a specific form of a student competition relating to design. Design competitions can be technical or purely aesthetic. The objective of technical competitions is to introduce students to real-world engineering situations and to teach students project-management and fabrication techniques used in industry. Aesthetic competitions usually require art and design skills.

Both students and industry benefit from intercollegiate design competitions.  Each competition allows students to apply the theories and information they have learning in the class room to real situations.  Industry gains better prepared and more experienced engineers.

History 

Through the 1970s only one competition of significance existed: Mini Baja.  Today, almost every field of engineering has several design competitions, which have extended from college down into high school (e.g., FIRST Robotics) and even younger grades (e.g., FIRST Lego League). The Society of Automotive Engineers organizes the largest design competitions, including Baja SAE, Sunryce, and Formula SAE.

Notable design competitions 

 Civil engineering
 Great Northern Concrete Toboggan Race
 Concrete canoe
 Steel bridge
 Mechanical engineering
 Baja SAE
 Basic Utility Vehicle
 Formula SAE
 Human Powered Vehicle Challenge (HPVC)
 ASABE International 1/4 Scale Tractor Student Design Competition

 Robotics Competitions
 DARPA Grand Challenge
 International Space Settlement Design Competition
 NASA's Lunabotics Competition
 RoboCup Soccer
 Multi-Disciplinary Competitions
 Stanford Center on Longevity Design Challenge

See also 
 Student competition
 University of Patras Formula Student Team - UoP Racing Team

Competitions
Student events
Isotropic etching. In semiconductor manufacturing, isotropic etching is a method commonly used to remove material from a substrate via a chemical process using an etchant substance. The etchant may be in liquid-, gas- or plasma-phase, although liquid etchants such as buffered hydrofluoric acid (BHF) for silicon dioxide etching are more often used. Unlike anisotropic etching, isotropic etching does not etch in a single direction, but rather etches in multiple directions within the substrate. Any horizontal component of the etch direction may therefore result in undercutting of patterned areas, and significant changes to device characteristics. Isotropic etching may occur unavoidably, or it may be desirable for process reasons.

References

Semiconductors
Tomlinson Holman. Tomlinson Miles Holman II (born 1946) is an American film theorist, audio engineer, and inventor of film technologies, notably the Lucasfilm's THX sound system. He developed the world's first 10.2 sound system.

Career
Early in his career, Holman developed what was known as the Holman Preamplifier for the APT Corporation, a former Massachusetts entity founded by Holman.  He holds a Bachelor of Science from the University of Illinois at Urbana–Champaign (1968).

In 2002 he received the Academy Award for Technical Achievement. Specifically, for "the research and system integration resulting in the improvement of motion picture loudspeaker systems".

In 2007 he received the IEEE Masaru Ibuka Award.

Holman taught film and television sound at the School of Cinematic Arts, University of Southern California from 1987 to 2011.

In 2011 - 2021, Softpedia reported that Apple Inc. had employed Holman, and speculated that this was to work on audio projects.

Books

 Sound for Film and Television (2001)
 Surround Sound: Up and Running (2008)

See also
James A. Moorer

References

External links
 Holman's current entertainment technology company
 Association for Computing Machinery Video Interviews with Tomlinson Holman

Living people
American acoustical engineers
USC School of Cinematic Arts faculty
University of Illinois Urbana-Champaign alumni
Academy Award for Technical Achievement winners
Film theorists
CAS Career Achievement Award honorees
1946 births
Lucasfilm people
Warren Abstract Machine. In 1983, David H. D. Warren designed an abstract machine for the execution of Prolog consisting of a memory architecture and an instruction set. This design became known as the Warren Abstract Machine (WAM) and has become the de facto standard target for Prolog compilers.

Purpose
The purpose of compiling Prolog code to the more low-level WAM code is to make subsequent interpretation of the Prolog program more efficient. Prolog code is reasonably easy to translate to WAM instructions, which can be more efficiently interpreted. Also, subsequent code improvements and compilations to native code are often easier to perform on the more low-level representation.

In order to write efficient Prolog programs, a basic understanding of how the WAM works can be advantageous. Some of the most important WAM concepts are first argument indexing and its relation to choice-points, tail call optimization, and memory reclamation on failure.

Memory areas
The WAM has the following memory areas:

 The global stack or heap, used to store compound terms
 The local stack for environment frames and choice-points
 The trail to record which variables bindings ought to be undone on backtracking

Example
Here is a piece of Prolog code:
 girl(sally).
 girl(jane).
 
 boy(B) :- \+ girl(B).
A WAM-based Prolog compiler will compile this into WAM instructions similar to the following:
 predicate(girl/1):
    switch_on_term(2,1,fail,fail,fail),
 label(1): switch_on_atom([(sally,3),(jane,5)])
 label(2): try_me_else(4)
 label(3): get_atom(sally,0)
           proceed
 label(4): trust_me_else_fail
 label(5): get_atom(jane,0)
           proceed
 
 predicate(boy/1):
    get_variable(x(1),0)
    put_structure(girl/1,0)
    unify_local_value(x(1))
    execute((\+)/1)])
An important characteristic of this code is its ability to cope with the various modes in which the predicates can be evoked: any argument might be a variable, a ground term, or a partly instantiated term. The "switch" instructions handle the different cases.

References

Logic programming
Abstract machines
Virtual machines
SRI International software
Cryptomathic. Cryptomathic is a software company specializing in the area of cryptography for e-commerce security systems. The company develops secure software for the financial and governmental industries. It focuses especially on developing back-end solutions using hardware security modules.

Cryptomathic has its headquarters in Aarhus, Denmark. The company was founded in 1986, by three professors from University of Aarhus, among them Peter Landrock and Ivan Damgård.  It now operates world-wide with offices in London, UK; Munich, Germany and San Jose, California, US

Cryptomathic has collaborated in research projects with the Isaac Newton Institute for Mathematical Sciences to develop Cryptomathic's systems for securing messaging between hardware security modules (HSMs). With Bristol University, Cryptomathic conducted research on authenticated encryption between HSMs.

Awards and recognition
In 2002, Cryptomathic's chief cryptographer Vincent Rijmen was named one of the top 100 innovators in the world under the age of 35 by the MIT Technology Review TR100.

In 2003, Cryptomathic was recognized by the World Economic Forum as a Technology Pioneer, based on its innovative product for mobile electronic signatures. The term "What You See Is What You Sign" (WYSIWYS) was coined in 1998 by Peter Landrock and Torben Pedersen of Cryptomathic during their work on delivering secure and legally binding digital signatures for Pan-European projects. In 2004, Cryptomathic received the Visa Smart Star Award for it contributions to the field of EMV and Chip and PIN based on its data preparation offering. In 2010, Cryptomathic's founder, Peter Landrock was named a Finalist for European Inventor 2010 in the "Lifetime Achievement" category by the European Patent Office.

The member of Cryptomathic's advisory board, Whitfield Diffie is co-author of the Diffie–Hellman key exchange, a method of securely exchanging cryptographic keys. Diffie and Hellman were awarded with the 2015 Turing Award for "fundamental contributions to modern cryptography" including public-key cryptography and digital signatures.

References

Cryptography companies
Companies based in Cambridge
Software companies established in 1986
1986 establishments in Denmark
Thortveitite. Thortveitite is a rare mineral consisting of scandium yttrium silicate (Sc,Y)2Si2O7. It is the primary source of scandium. Occurrence is in granitic pegmatites. It was named after Olaus Thortveit, a Norwegian engineer. It is grayish-green, black or gray in color.

A transparent gem quality example was found in 2004, and reported in The Journal of Gemmology.

See also
List of minerals
List of minerals named after people

References

Scandium minerals
Yttrium minerals
Sorosilicates
Monoclinic minerals
Minerals in space group 12
Euxenite. Euxenite, or euxenite-(Y) (the official mineralogical name), is a brownish black mineral with a metallic luster.

Chemistry
It contains calcium, niobium, tantalum, cerium, titanium, yttrium, and typically uranium and thorium, with some other metals. The chemical formula is . It is commonly partially amorphous due to radiation damage.

Euxenite forms a continuous series with the titanium rich polycrase-(Y) having the formula .

Name and discovery
It was first described in 1870 and named for from the Greek (εὔξενος), hospitable or friendly to strangers, in allusion to the many rare elements that it contains.

Occurrence
It occurs in granite pegmatites and detrital black sands.

It is found in many locations worldwide, notably its type locality in  	Jølster, Sunnfjord, Norway. Other locations include the Ural Mountains of Russia; Sweden; Minas Gerais, Brazil; Ampangabe, Madagascar; Ontario, Canada; and in Arizona, Wyoming and Colorado in the US.

Use
Euxenite is used as an ore of the rare earth elements it contains. Rare large crystals have also been used in jewelry.

References

Calcium minerals
Thorium minerals
Uranium minerals
Lanthanide minerals
Niobium minerals
Tantalum minerals
Titanium minerals
Yttrium minerals
Cerium minerals
Oxide minerals
Orthorhombic minerals
Minerals in space group 62
Minerals described in 1870
Gadolinite. Gadolinite, sometimes known as ytterbite, is a silicate mineral consisting principally of the silicates of cerium, lanthanum, neodymium, yttrium, beryllium, and iron with the formula . It is called gadolinite-(Ce) or gadolinite-(Y), depending on the prominent composing element (Y if yttrium predominates, and Ce if cerium). It may contain 35.5% yttria sub-group rare earths, 2.2% ceria earths, as much as to 11.6% BeO, and traces of thorium. It is found in Sweden, Norway, and the US (Texas and Colorado).

Characteristics
Gadolinite is fairly rare and typically occurs as well-formed crystals. It is nearly black in color and has a vitreous luster. The hardness is between 6.5 and 7 on the Mohs scale, and the specific gravity is between 4.0 and 4.7. It fractures in a conchoidal pattern and streaks grayish-green. It was also thought to exhibit pyrognomic properties, as it can emit visible light when heated to relatively low temperatures, but the scientific consensus is that this is the product of thermoluminescence.

Name and discovery
Gadolinite was named in 1800 for Johan Gadolin, the Finnish mineralogist-chemist who first isolated an oxide of the rare-earth element yttrium from the mineral in 1792. The rare earth gadolinium was also named after him. However, gadolinite does not contain more than trace amounts of gadolinium. When Gadolin analyzed this mineral, he missed an opportunity to discover a second element: the element he thought was aluminium (alumina) was in fact beryllium (beryllia), an element that was not officially identified until 1798.

Several elements were discovered as a consequence of lengthy analysis and decomposition of the ore gadolinite. As the ore was progressively analysed, the residue was first given the label ceria, then lanthana, and subsequently yttria, erbia, and terbia. In order of date discovered, the list of elements includes cerium, lanthanum, erbium, terbium, yttrium, ytterbium, holmium, thulium, scandium, praseodymium, neodymium and dysprosium. Several of these new elements were either discovered or isolated by Carl Gustaf Mosander in the 1830s and 1840s.

Uses
Gadolinite and euxenite are quite abundant and are future sources of yttrium sub group rare earths. At present, these elements are recovered from monazite concentrates (after recovery of ceria sub-group metals).

See also
 List of minerals
 List of minerals named after people

References

Further reading
 Gadolinite–(Ce) on Handbook of Mineralogy
 Gadolinite–(Y) on Handbook of Mineralogy
 Gadolinite–(Ce) on Mindat
 Gadolinite–(Y) on Mindat
 Gallery of Minerals

Lanthanide minerals
Beryllium minerals
Iron(II) minerals
Nesosilicates
Monoclinic minerals
Minerals in space group 14
Minerals described in 1800
Rc (Unix shell). rc (for "run commands") is the command line interpreter for Version 10 Unix and Plan 9 from Bell Labs operating systems. It resembles the Bourne shell, but its syntax is somewhat simpler. It was created by Tom Duff, who is better known for an unusual C programming language construct ("Duff's device").

A port of the original rc to Unix is part of Plan 9 from User Space.  A rewrite of rc for Unix-like operating systems by Byron Rakitzis is also available but includes some incompatible changes.

Rc uses C-like control structures instead of the original Bourne shell's ALGOL-like structures, except that it uses an if not construct instead of else, and has a Bourne-like for loop to iterate over lists. In rc, all variables are lists of strings, which eliminates the need for constructs like "$@". Variables are not re-split when expanded. The language is described in Duff's paper.

Influences

es
es (for "extensible shell") is an open source, command line interpreter developed by Rakitzis and Paul Haahr that uses a scripting language syntax influenced by the rc shell.  It was originally based on code from Byron Rakitzis's clone of rc for Unix.

Extensible shell is intended to provide a fully functional programming language as a Unix shell. It does so by introducing "program fragments" in braces as a new datatype, lexical scoping via let, and some more minor improvements. The bulk of es development occurred in the early 1990s, after the shell was introduced at the Winter 1993 USENIX conference in San Diego.  Official releases appear to have ceased after 0.9-beta-1 in 1997, and es lacks features present in more popular shells, such as zsh and bash. A public domain fork of  is active .

Examples
The Bourne shell script:

if [ "$1" = "hello" ]; then
    echo hello, world
else
    case "$2" in
    1) echo $# 'hey' "jude's"$3;;
    2) echo `date` :$*: :"$@":;;
    *) echo why not 1>&2
    esac
    for i in a b c; do
        echo $i
    done
fi

is expressed in rc as:

if(~ $1 hello)
    echo hello, world
if not {
    switch($2) {
    case 1
        echo $#* 'hey' 'jude''s'^$3
    case 2
        echo `{date} :$"*: :$*:
    case *
        echo why not >[1=2]
    }
    for(i in a b c)
        echo $i
}

Rc also supports more dynamic piping:

 a |[2] b    # pipe only standard error of a to b — equivalent to '3>&2 2>&1 >&3 | b' in Bourne shell
 a <>b       # opens file b as a's standard input and standard output
 a <{b} <{c} # becomes a {standard output of b} {standard output of c},
             # better known as "process substitution"

References

External links
 - Plan 9 manual page
Plan 9 from User Space - Includes rc and other Plan 9 tools for Linux, Mac OS X and other Unix-like systems
Byron Rakitzis' rewrite for Unix (article )
es Official website

Free system software
Inferno (operating system)
Plan 9 from Bell Labs
Procedural programming languages
Programming languages created in 1989
Scripting languages
Text-oriented programming languages
Unix shells
Dispersion (materials science). In materials science, dispersion is the fraction of atoms of a material exposed to the surface.  In general, D = NS/N, where D is the dispersion, NS is the number of surface atoms and NT is the total number of atoms of the material. It is an important concept in heterogeneous catalysis, since only atoms exposed to the surface can affect catalytic surface reactions. Dispersion increases with decreasing crystallite size and approaches unity at a crystallite diameter of about 0.1 nm.

See also
 Emulsion dispersion

References

Materials science
Subsonic. Subsonic may refer to:

Motion through a medium
 Any speed lower than the speed of sound within a sound-propagating medium
 Subsonic aircraft, a flying machine that flies at air speeds lower than the speed of sound
 Subsonic ammunition, a type of bullet designed to avoid creating a loud shockwave when fired
 Subsonic flight, an aircraft flight at air speeds lower than the speed of sound in air
 Subsonic and transonic wind tunnels

Music
 Subsonic (album), a 2002 album by Vigleik Storaas Trio
 Subsonic (EP), a 2013 EP by Younha
 Subsonic album series:
 Subsonic 2: Bass Terror, a 1995 album by Bill Laswell and Nicholas Bullen
 Subsonic 3: Skinner's Black Laboratories, a 1995 album by Andy Hawkins and Justin Broadrick
 Subsonic Music Festival, an annual electronic music festival in Monkerai, Australia

See also
 Infrasound, sound at frequencies below the normal threshold of human hearing
Call Level Interface. The Call Level Interface (CLI) is an application programming interface (API) and software standard to embed Structured Query Language (SQL) code in a host program as defined in a joint standard by the International Organization for Standardization (ISO) and International Electrotechnical Commission (IEC): ISO/IEC 9075-3:2003. The Call Level Interface defines how a program should send SQL queries to the database management system (DBMS) and how the returned recordsets should be handled by the application in a consistent way. Developed in the early 1990s, the API was defined only for the programming languages C and COBOL.

The interface is part of what The Open Group, publishes in a part of the X/Open Portability Guide, termed the Common Application Environment, which is intended to be a wide standard for programming open applications, i.e., applications from different programming teams and different vendors that can interoperate efficiently. SQL/CLI provides an international standard implementation-independent CLI to access SQL databases. Client–server tools can easily access databases through dynamic-link libraries (DLL). It supports and encourages a rich set of client–server tools.

The most widespread use of the CLI standard is the basis of the Open Database Connectivity (ODBC) specification, which is widely used to allow applications to transparently access database systems from different vendors. The current version of the API, ODBC 3.52, incorporates features from both the ISO and X/Open standards. Examples of languages that support Call Level Interface are ANSI C, C#, Visual Basic .NET (VB.NET), Java, Pascal, and Fortran.

History
The work with the Call Level Interface began in a subcommittee of the US-based SQL Access Group (SAG) In 1992, it was initially published and marketed as Microsoft's ODBC API. The CLI specification was submitted as to the ISO and American National Standards Institute (ANSI) standards committees in 1993. The standard has the book number  and the internal document number is C451.

ISO SQL/CLI is an addendum to 1992 SQL standard (SQL-92). It was completed as ISO standard ISO/IEC 9075-3:1995 Information technology—Database languages—SQL—Part 3: Call-Level Interface (SQL/CLI). The current SQL/CLI effort is adding support for SQL3.

In the fourth quarter of 1994, control over the standard was transferred to the X/Open Company, which significantly expanded and updated it. The X/Open CLI interface is a superset of the ISO SQL CLI.

References

External links
Online definition of CLI at The Open Group webpage

SQL
Open Group standards
Nroff. nroff (short for "new roff") is a text-formatting program on Unix and Unix-like operating systems. It produces output suitable for simple fixed-width printers and terminal windows. It is an integral part of the Unix help system, being used to format man pages for display.

nroff and the related troff were both developed from the original roff. While nroff was intended to produce output on terminals and line printers, troff was intended to produce output on typesetting systems. Both used the same underlying markup and a single source file could normally be used by nroff or troff without change.

History
nroff was written by Joe Ossanna for Version 2 Unix, in Assembly language and then ported to C.

It was a descendant of the RUNOFF program from CTSS, the first computerized text-formatting program, and is a predecessor of the Unix troff document processing system.

There is also a free software version of nroff in the groff package.

Variants
The Minix operating system, among others, uses a clone of nroff called cawf by Vic Abell, based on awf, the Amazingly Workable Formatter designed in awk by Henry Spencer. These are not full replacements for the nroff/troff suite of tools, but are sufficient for display and printing of basic documents and manual pages.

In addition, a simplified version of nroff is available in Ratfor source code form as an example in the book Software Tools by Brian Kernighan and P. J. Plauger.

See also
 troff
 groff
 TeX
 LaTeX
 man page

References

External links
 source code for Henry Spencer's AWF
 troff/nroff quick reference
 nroff source code in Illumos. Explanation by Bryan Cantrill

Troff
Assembly language software
Markup languages
Unix text processing utilities