omniomni/omni-engineering huggingface dataset:
NaviServer. NaviServer is a high performance web server written in C and Tcl. It can be easily extended in either language to create web sites and services; there are over 35 modules available (including database integration or protocol support for UDP, SMTP, LDAP, DNS, COAP, etc.)

The project is under active development,
NaviServer is mostly written in C with a very well-commented source code, had more than 6,000 commits made by 35 contributors
representing more than 100,000 lines of code. NaviServer is licensed under the terms of the Mozilla Public License (MPL).

Recent new features include:
 an internal watchdog for automatic server restarts
 server internals exposed in a command line mode
 thread shared arrays (atomic operations, dict support)
 built-in caching with cache transaction semantics (cache commit/rollback)
 hot code swapping (update code in the running system without server restart)
 asynchronous spooling of requests and replies
 delivery of static files optionally with gzip or brotli compression with automatic re-compression on updates
 selective logging with color highlighting (non-blocking)
 efficient built-in crypto support
 mass virtual hosting
 byte-range requests for streaming and resumption of downloads
 rich HTTPS support (server and client-side SNI, OCSP Stapling)
 built-in HTTP/HTTPS client support, with log-files
 built-in statistics (for mutex locks/rwlocks, cache, db-handles, ...)
 bandwidth management via multiple connection thread pools
 WebSocket and IPv6 support

History
NaviServer is based on AOLserver (version 4.10), AOL's open-source web server. The NaviServer project started as a fork of the AOLserver project in July 2005. It is different by supporting multiple protocols, providing higher scalability through asynchronous I/O and aims to be less conservative with new feature development.

Historically NaviServer was the original name of the server, a closed-source product by a company called NaviSoft in the early 1990s. It was bought by AOL in 1995, and released as open-source in 1999 as AOLserver after they released Mozilla. This friendly-fork takes the code back to its original name.

Large applications of NaviServer are the ArsDigita Community System and OpenACS in particular.

See also
 Comparison of web servers

External links
 NaviServer Home page
 NaviServer GitHub Repository
 NaviServer Bitbucket Repository
 NaviServer Documentation

References

Free web server software
Free software programmed in C
Free software programmed in Tcl
Rutan Defiant. The Rutan Model 40 Defiant is a four-seat, twin-engine homebuilt aircraft with the engines in a push-pull configuration.  It was designed by aerospace engineer Burt Rutan for the Rutan Aircraft Factory.

Development

The prototype Defiant, N78RA, was first flown on 30 June 1978. It had been intended as a proof-of-concept of a very safe light twin design, requiring little trim change and no pilot action in case of engine failure, and with good single engine performance. A comparison of the Defiant single engine climb rate with a Gulfstream Cougar had shown about  vs  per minute at low altitude with both aircraft in a clean, gear up and flaps up, configuration. The prototype is now owned by the Hiller Aviation Museum.

In 1979 the Rutan Aircraft Factory announced they would proceed with certification of a Defiant-based light twin. Adequate financing was not secured for this project, and the design was modified for homebuilt construction as the Model 74, with the second aircraft (built by Fred Keller) appearing at Oshkosh 1983. Plans were offered in mid-1984. 176 sets of plans were purchased before RAF discontinued selling plans in 1985. Nine examples were known to be flying as of mid-1987. Nineteen are registered with the FAA as of 2005.

Design
The Defiant is built using fiberglass layup over Styrofoam core shapes in the same manner as the Rutan VariEze. The main gear is fixed, and there are no flaps. The Propellers are fixed-pitch non-feathering, which is unusual in a twin-engine design. Cockpit entry is through a side hinged canopy. The winglets provide yaw stability. Unusually, the Defiant has a ventral, port offset, forward mounted rudder, as can be seen in pictures of the plane taxiing.

Specifications (Defiant)

References

 Aerofiles information

Defiant
1970s United States civil utility aircraft
Twin-engined push-pull aircraft
Canard aircraft
Mid-wing aircraft
Aircraft first flown in 1978
Opuha Dam. The Opuha Dam is located on the Opuha River, a tributary of the Ōpihi River in South Canterbury, New Zealand. The dam is used for water storage for farming irrigation and provides 7.7 MW of electricity to New Zealand's national grid.  The site has been identified as an Important Bird Area by BirdLife International because it supports breeding colonies of the endangered black-billed gull.

History
The dam failed during construction on 6 February 1997 due to heavy rain. It was completed in 1998, creating Lake Opuha.

In 2003 in order to counteract oxygen depletion in the lake an aeration system was installed.

References

External links
IPENZ report on emergency management.

1998 establishments in New Zealand
Buildings and structures in the Canterbury Region
Dams in New Zealand
Irrigation in New Zealand
Dam failures in Oceania
1997 industrial disasters
1997 in New Zealand
Dams completed in 1998
Important Bird Areas of New Zealand
1997 disasters in New Zealand
Boo (programming language). Boo is an object-oriented, statically typed, general-purpose programming language that seeks to make use of the Common Language Infrastructure's support for Unicode, internationalization, and web applications, while using a Python-inspired syntax and a special focus on language and compiler extensibility. Some features of note include type inference, generators, multimethods, optional duck typing, macros, true closures, currying, and first-class functions.

Boo was one of the three scripting languages for the Unity game engine (Unity Technologies employed De Oliveira, its designer), until official support was dropped in 2014 due to the small userbase. The Boo Compiler was removed from the engine in 2017. Boo has since been abandoned by De Oliveira, with development being taken over by Mason Wheeler.

Boo is free software released under the BSD 3-Clause license. It is compatible with the Microsoft .NET and Mono frameworks.

Syntax 

print ("Hello World")

def fib():
    a, b = 0L, 1L   h
    # The 'L's make the numbers double word length (typically 64 bits)
    while true:
        yield b
        a, b = b, a + b

# Print the first 5 numbers in the series:
for index as int, element in zip(range(5), fib()):
    print("${index+1}: ${element}")

See also 

 Fantom
 Apache Groovy
 IronPython
 IronRuby
 Nemerle
 REBOL
 StaDyn

References

External links 

 Official website
 How To Think Like a Computer Scientist: Learning to Program with Boo
 Boo Succinctly Revealed
 Bootorial

Programming languages
.NET programming languages
Brazilian inventions
Class-based programming languages
Free and open source compilers
Object-oriented programming languages
Procedural programming languages
Programming languages created in 2003
Software using the BSD license
Statically typed programming languages
2003 software
Vibrational energy relaxation. Vibrational energy relaxation, or vibrational population relaxation, is a process in which the population distribution of molecules in quantum states of high energy level caused by an external perturbation returns to the Maxwell–Boltzmann distribution.

In solution, the process proceeds with intra- and intermolecular energy transfer. The excess energy of the excited vibrational mode is transferred to the kinetic modes in the same molecule or to the surrounding molecules. Through this process, the initially excited vibrational mode moves to a vibrational state of a lower energy. The relaxation is called the longitudinal relaxation, and the time constant of the relaxation is called the longitudinal relaxation time, or T1.

Vibrational energy relaxation has been studied with time-resolved spectroscopy. By the excitation of the pump pulse, the population distribution of the vibrationally excited state is made by infrared absorption or a Raman process when the molecule is in the electronic ground state. In addition, by the electronic transition, the molecule often moves to the vibrationally excited state of the electronic excited state. The process of the energy relaxation from these vibrationally excited states can be observed with the probe pulse, which is delayed from the pump pulse.

References

Molecular physics
Vibrational spectroscopy
Emission spectroscopy
AVCEN Jetpod. The AVCEN Jetpod was a design proposal for a very quiet aircraft that could take off and land in short distances (STOL), developed by Avcen Limited, a company incorporated on 18 October 1988 which became a subsidiary of the Hong Kong–based company, Profit Sky Group Ltd. 

A number of applications were proposed, including as a military transport, an executive transport, and as a short to medium-range air taxi. Avcen Limited was the British-based headquarters while Avcen Limited Malaysia was based at Patimas Technology Centre, Technology Park, Bukit Jalil, Kuala Lumpur. According to Avcen's publicity materials, the Jetpod's maximum speed was designed to be . It would need only  to take-off or land, allowing runways to be constructed close to the center of major cities, and would be sufficiently quiet to not be noticeable above city traffic. 

At 12:30 p.m. on the 16th of August, 2009 a just-completed prototype Jetpod crashed, killing the founder of Avcen, Michael Robert Dacre, who was the sole occupant. Dacre had attempted to take off three times and on the fourth successfully lifted off and climbed to 200 meters. then the aircraft became uncontrollable and crashed.   According to Taiping deputy police chief Syed A. Wahab Syed A. Majid, the company had not obtained permission from the Royal Malaysian Air Force to conduct the flight tests.

References

External links
Video of the crash showing what craft looked like before takeoff
Another video of the crash from a different angle
Video of the crash aftermath
Gizmag article on the jetpod
Avcen Limited's website
CAD Images of the "jet pod"

Proposed aircraft of the United Kingdom
Aircraft flown once
Vickers Valentia. The Vickers Valentia was a 1920s British flying boat designed during the First World War.

History
Three Valentia prototypes were built by the Vickers Company at their Barrow works (Walney Island perhaps), having been ordered in May 1918 as a potential replacement for the Felixstowe F.5. The hull was built by S.E.Saunders works at Cowes. The first of the three (Serial Number N124) first flew on 5 March 1921, when Stanley Cockerell began test-flying it over the Solent. N124 was damaged on landing in June 1921 and was dismantled, the second N125 forced landed on its delivery flight on 15 March 1922 The third flying boat N126 was delivered in 1923 and used for trials until it was withdrawn from use in November 1924.

The name was later re-used for a transport aircraft, the Vickers Type 264 Valentia.

Specifications (Valentia)

See also

References

Andrews, C.F and Morgan, E.B. Vickers Aircraft since 1908. London:Putnam, 1988. .
London, Peter. British Flying Boats. Stroud, UK:Sutton Publishing, 2003. .

1920s British patrol aircraft
Flying boats
Valentia
Biplanes
Aircraft first flown in 1921
Twin piston-engined tractor aircraft
Tamper (tool). A tamper is a device used to compact or flatten an aggregate or another powdered or granular material, typically to make it resistant to further compression or simply to increase its density.

Examples
 Small, handheld tampers are used to compress ground coffee into a puck to prepare espresso.  

 Manual or powered tampers compact gravel before laying a concrete or brick patio or walkway so that the underlying gravel layer does not settle over time, or compress the fill in a utility trench as seen in the illustration.  
 Self-propelled, mechanised ballast tamping machines, which compact the ballast underneath rail tracks.
 Preparing some firearms and artillery pieces for firing may involve tamping the charge, such as explosive material or a projectile, into the barrel. For example, muzzle loaders.
 A fireplace can be tamped with a poker or similar tool to compress the material being burned (wood, coal, peat etc...).  This improves the heat/burning efficiency, by reducing the volume of burning material that is exposed to airflow.  This is often confused with damping - which involves reducing the intensity of the burn by restricting the flue or by the use of any fire retarding material such as water.

Tampers in construction 
Within the construction field, different types of tampers can be used for different purposes, spaces, and materials.

 A jumping jack, or rammer, is a relatively small, hand-operated compactor. It uses vibratory force, which is when mechanical force is used in addition to the machine's weight to compact the materials. The jumping jack is composed of a motor, handle, and head. When the motor is started, the head is moved up and down, and the operator steers the machine around the desired area. Jumping jacks work well in small areas and are good for cohesive soil, or soil with a large clay content. The video shows a jumping jack being used in construction to prepare for paving.
 A plate compactor, or plate tamp, is another hand-operated compactor that also uses vibratory force. The plate compactor consists of a handle and head that holds the motor. When started, the plate moves up and down within the head, and the operator pushes the compactor around the desired area. Plate compactors work best with granular soils, such as gravel and sand. They come in a variety of sizes due to the flexibility of the push motion. Vibratory plate compactors are the lightest and best for smaller projects, while heavy-duty plate compactors exert the most force and work well for large-scale projects, such as paving.
 A handheld tamper is a small compactor that utilizes static force, which is when only the dead weight of the equipment and pressure the operator applies to it compact the materials. These tampers do not have a motor, only a flat plate attached to a handle. The plate is placed on the material the operator wishes to compact and pressed down. Handheld tampers are best used with soil and other small-scale projects due to the lack of great force from mechanical elements.

See also 
 Compactor
 Sand rammer

References

Tools
Articles containing video clips
4D. 4D or 4-D primarily refers to:

 4-dimensional spacetime: three-dimensional space of length, width, and height, plus time
 Four-dimensional space

It may also refer to:

Computers and photography
 4D (software), a complete programming environment including database and web server
 4D SAS, developers of 4D and Wakanda
 4D Inc, a US-based subsidiary of 4D SAS
 4D BIM, a term used in computer aided design
 4D printing
 Cinema 4D, a commercial cross platform 3D graphics application
 SGI IRIS 4D, a line of workstations from Silicon Graphics
 4D, a photo print size for digital cameras

Arts and entertainment
 4D (album), a 2010 album by Matthew Shipp
 "4-D" (The X-Files), an episode of The X-Files
 4D Audio Recording system, an audio recording system developed by Deutsche Grammophon
 4D film, a high technology film experience augmented with physical or environmental effects
 4DTV, a satellite TV broadcasting technology from Motorola
 4DX, a 4D film format
 "4D", a song by Grand Mixer DXT and Bill Laswell from Aftermathematics (2003)
 "4D", a song by Northlane from Alien (2019)
 4D, the production code for the 1975 Doctor Who serial Revenge of the Cybermen

Other
 Class 4-D, a classification of the Selective Service System
 4-D (psychedelic), a psychedelic drug
 4D (train) in Melbourne, Australia
 4-Digits, a lottery in Malaysia and Singapore
 Air Sinai (IATA: 4D)
 Ring finger, the fourth digit (abbreviated 4D) of the hand
 Potez 4D, a four-cylinder aircraft engine

See also
 D4 (disambiguation)
 DDDD (disambiguation)
 Fourth dimension (disambiguation)
 Four Dimensions (disambiguation)
DFL (disambiguation). DFL primarily refers to the Minnesota Democratic–Farmer–Labor Party, an affiliate of the U.S. Democratic Party. It may also refer to:

 Cosworth DFL, a variant of the Cosworth DFV Formula One engine, intended for Group C racing
 David Florida Laboratory, a Canadian aerospace laboratory
 Degree of financial leverage, a metric of leverage (finance)
 Dead Fucking Last, a US punk band
 Democrats for Life, an organization of anti-abortion Democrats
 Design for logistics, a supply-chain management concept
 Deutsche Fußball Liga, operator of the German Fußball-Bundesliga
 Dongfeng Motor Co., Ltd., a joint-venture between Dongfeng and Nissan
 Dunfermline Queen Margaret railway station, National Rail station code DFL, in Scotland
A.V. Roe. A.V. Roe may refer to:

 Alliott Verdon Roe, British aircraft pioneer and manufacturer
 A.V. Roe and Company (generally known as Avro): British aircraft manufacturer founded by Alliott Verdon Roe
 A.V. Roe Canada (known as Avro Canada): Canadian subsidiary of Hawker Siddeley (the parent of Avro)
Schwing. Schwing may refer to:

People 
Anna-Lena Schwing (born 1996), German actress
Carl Georg Schwing (1778–1858), German jurist and mayor of Stralsund
Hans-Elmar Schwing (born 1972), German chess player
Hellmuth Schwing, German infantry commander
Roland Schwing (1949–2017), German politician
William Schwing Patout III (1932–2017), American businessman and agricultural engineer

Companies 
Folmer and Schwing Manufacturing Company, later Graflex
Schwing (company), German manufacturer of concrete pumps and truck mixers
Schwing Stetter, German manufacturer of concrete mixers and concrete transport systems

Other uses 
An exclamation used in the Wayne's World sketches and films
German exonym for Žminj in Croatia
BRL-CAD. BRL-CAD is a constructive solid geometry (CSG) solid modeling computer-aided design (CAD) system. It includes an interactive geometry editor, ray tracing support for graphics rendering and geometric analysis, computer network distributed framebuffer support, scripting, image-processing and signal-processing tools. The entire package is distributed in source code and binary form.

Although BRL-CAD can be used for a variety of engineering and graphics applications, the package's primary purpose continues to be the support of ballistic and electromagnetic analyses. In keeping with the Unix philosophy of developing independent tools to perform single, specific tasks and then linking the tools together in a package, BRL-CAD is basically a collection of libraries, tools, and utilities that work together to create, raytrace, and interrogate geometry and manipulate files and data. In contrast to many other 3D modelling applications, BRL-CAD primarily uses CSG rather than boundary representation. This means BRL-CAD can "study physical phenomena such as ballistic penetration and thermal, radiative, neutron, and other types of transport". It does also support boundary representation.

The BRL-CAD libraries are designed primarily for the geometric modeler who also wants to tinker with software and design custom tools. Each library is designed for a specific purpose: creating, editing, and ray tracing geometry, and image handling. The application side of BRL-CAD also offers a number of tools and utilities that are primarily concerned with geometric conversion, interrogation, image format conversion, and command-line-oriented image manipulation.

History

In 1979, the U.S. Army Ballistic Research Laboratory (BRL) expressed a need for tools that could assist with the computer simulation and engineering analysis of combat vehicle systems and environments.  When no CAD package was found to be adequate for this purpose, BRL software developers – led by Mike Muuss – began assembling a suite of utilities capable of interactively displaying, editing, and interrogating geometric models.  This suite became known as BRL-CAD. Development on BRL-CAD as a package subsequently began in 1983; the first public release was made in 1984.  BRL-CAD became an open-source project in December 2004.

The BRL-CAD source code repository is the oldest known public version-controlled codebase in the world that's still under active development, dating back to 1983-12-16 00:10:31 UTC.

See also 

 PLaSM - Programming Language of Solid Modeling
 Comparison of CAD editors

References

External links
 
 

Computer-aided design software for Linux
Computer-aided design software
Engineering software that uses Qt
Free computer-aided design software
Free software programmed in C
Free software programmed in Tcl
MacOS computer-aided design software
Software that uses Tk (software)
Software using the BSD license
Heathrow arrival stacks. Inbound aircraft to London Heathrow Airport typically follow one of a number of Standard Terminal Arrival Routes (STARs). The STARs each terminate at one of four different RNAV waypoints (co-located with VOR navigational aids), and these also define four "stacks" where aircraft can be held, if necessary, until they are cleared to begin their approach to land.  Stacks are sections of airspace where inbound aircraft will normally use the pattern closest to their arrival route. They can be visualised as an invisible helix in the sky. Each stack descends in  intervals from  down to . If these holds become full, aircraft are held at more distant points before being cleared onward to one of the four main holds.

The stacks

Bovingdon
The Bovingdon stack is for arrivals from the north west. It extends above the village of Bovingdon and the town of Chesham, and uses the RNAV waypoint BNN (co-located with the BNN VOR), which is situated on the former RAF Bovingdon airfield.

Biggin Hill
The Biggin Hill stack on the south east edge of Greater London is for arrivals from the south east.  It uses the RNAV waypoint BIG (co-located with the BIG VOR), which is situated on London Biggin Hill Airport.

Lambourne
The Lambourne stack in Essex is for arrivals from the north east.  It uses the RNAV waypoint LAM (co-located with the LAM VOR), which is situated adjacent to Stapleford Aerodrome.

Ockham

The Ockham stack in Surrey is for arrivals from the south west.  It uses the RNAV waypoint OCK (co-located with the OCK VOR), which is situated on the former Wisley Airfield. During typical easterly operations, the proximity of arrival traffic via OCK requires departures from Heathrow's runway 09R towards the Compton VOR (CPT) to follow a non-standard departure procedure.

Developments
The arrival procedures are being revised since 2014 to reduce stacking by introducing variable speed limits and alternative holding procedures.

Incidents
At 6 am on 1 December 2003, a major disaster in the stack was narrowly avoided when two planes, carrying a total of 500 passengers, flew within  of vertical clearance. An air traffic controller was blamed by a later inquiry for misdirecting traffic when he ordered a United Airlines Boeing 777 into a level of the Bovingdon Hold already occupied by a similar British Airways aircraft.

References

Further reading
 Howell, G. (1976). Future system consideration for operations of aircraft in the terminal movement area. The Aeronautical Journal, 80(782), 51–60. doi:10.1017/S0001924000033480

External links

London 24 - Layers of London air traffic, NATS, 2014

Air traffic control in the United Kingdom
Aviation in London
Aviation in England
Heathrow Airport