omniomni/omni-engineering huggingface dataset:
Non-evaporable getter. Non evaporable getters (NEG), based on the principle of metallic surface sorption of gas molecules, are mostly porous alloys or powder mixtures of Al, Zr, Ti, V and Fe. They help to establish and maintain vacuums by soaking up or bonding to gas molecules that remain within a partial vacuum. This is done through the use of materials that readily form stable compounds with active gases. They are important tools for improving the performance of many vacuum systems. Sintered onto the inner surface of high vacuum vessels, the NEG coating can be applied even to spaces that are narrow and hard to pump out, which makes it very popular in particle accelerators where this is an issue. The main sorption parameters of the kind of NEGs, like pumping speed and sorption capacity, have low limits.

A different type of NEG, which is not coated, is the Tubegetter. The activation of these getters is accomplished mechanically or at a temperature from 550 K. The temperature range is from 0 to 800 K under HV/UHV conditions.

The NEG acts as a getter or getter pump that is able to reduce the pressure to less than 10−12 mbar.

Non-evaporable getters, which work at high temperature, generally consist of a film of a special alloy, often primarily zirconium; the requirement is that the alloy materials must form a passivation layer at room temperature which disappears when heated.
Common alloys have names of the form St (Stabil) followed by a number:
St 707 is 70% zirconium, 24.6% vanadium, and the balance iron.
St 787 is 80.8% zirconium, 14.2% cobalt, and the balance mischmetal.
St 101 is 84% zirconium and 16% aluminium.
In tubes used in electronics, the getter material coats plates within the tube which are heated in normal operation; when getters are used within more general vacuum systems, such as in semiconductor manufacturing, they are introduced as separate pieces of equipment in the vacuum chamber, and turned on when needed.
Deposited and patterned getter material is being used in microelectronics packaging to provide an ultra-high vacuum in a sealed cavity. To enhance the getter pumping capacity, the activation temperature must be maximized, considering the process limitations.

It is, of course, important not to heat the getter when the system is not already in a good vacuum.

See also
 Ion pump (physics)

References

External links 

 Video: Non-Evaporable Getter (NEG) Operation
 Folder: TubeGetter

Vacuum
Bicycle Torque Coupling. An S and S Coupling also known as a Bicycle Torque Coupling or BTC is a coupling which enables bicycle frames to be separated into smaller pieces, usually to facilitate packing and transporting. Couplings can be built into the frame by the frame manufacturer when the frame is made or can be added to a frame after it is finished. A special spanner is available for tightening and loosening the couplings.

Applications
The couplings are usually installed in the top tube and down tube of a single-rider diamond frame. This enables the bicycle to be boxed small enough to avoid the extra fee most airlines charge to check a bicycle as luggage. They can also be installed in tandem and recumbent frames. Santana manufactures a "triplet (or quad) that can be transformed into a tandem by simply removing the center section of the frame."

Characteristics
The couplings are available in stainless steel, cromoly steel, and titanium and in different sizes, from  to match the frame tubing in which they are installed. They weigh about  per pair, and arc as strong as uncoupled tubing. They use a Hirth joint to resist torsion.

It takes a few minutes to separate the couplings.

Alternatives
In order to support the ovalized tube Santana Cycles uses between the bottom bracket shells of their tandems, they have developed their own oval couplers.

See also 
Folding bicycle
Recumbent bicycle
Tandem bicycle
Touring bicycle

References

External links
 http://www.sandsmachine.com/ S and S Machine Bicycle Torque Couplings (BTCs)
 http://www.bikecad.ca/boxes Determining the placement of couplings in BikeCAD

Coupler
Acoustic rheometer. An acoustic rheometer is a device used to measure the rheological properties of fluids, such as viscosity and elasticity, by utilizing sound waves. It works by generating acoustic waves in the fluid and analyzing the changes in the wave propagation caused by the fluid's rheological behavior. An acoustic rheometer uses a piezo-electric crystal to generate the acoustic waves, applying an oscillating extensional stress to the system. System response can be interpreted in terms of extensional rheology.
 
This interpretation is based on a link between shear rheology, extensional rheology and acoustics. Relationship between these scientific disciplines was described in details by Litovitz and Davis in 1964.

It is well known that properties of viscoelastic fluid are characterised in shear rheology with a shear modulus G, which links shear stress Tij and shear strain Sij
 

There is similar linear relationship in extensional rheology between extensional stress P, extensional strain S and extensional modulus K:

Detail theoretical analysis indicates that propagation of sound or ultrasound through a viscoelastic fluid depends on both shear modulus G and extensional modulus K. It is convenient to introduce a combined longitudinal modulus M:

There are simple equations that express longitudinal modulus in terms of acoustic properties, sound speed V and attenuation α

Acoustic rheometer measures sound speed and attenuation of ultrasound for a set of frequencies in the megahertz range. These measurable parameters can be converted into real and imaginary components of longitudinal modulus.

Sound speed determines M', which is a measure of system elasticity. It can be converted into fluid compressibility.
Attenuation determines M", which is a measure of viscous properties, energy dissipation. This parameter can be considered as extensional viscosity
In the case of Newtonian liquid attenuation yields information on the volume viscosity. Stokes' law (sound attenuation) provides relationship among attenuation, dynamic viscosity and volume viscosity of the Newtonian fluid.

This type of rheometer works at much higher frequencies than others. It is suitable for studying effects with much shorter relaxation times than any other rheometer.

References

See also
Rheology

Measuring instruments
Photographic Activity Test. Photographic Activity Test (PAT) is an ISO standard test detailed in ISO 18916:2007 (E), updated in 2007. Previous versions of the standard were numbered ISO 14523:1999(E).

The test evaluates materials for archival quality and their use in photographic enclosures.  Many different types of materials can be tested including: paper, boards, plastic, adhesives, pens, stickers, labels, paints and inks. The test involves incubating samples and detectors in a high-temperature, high-humidity accelerated aging environment.

References

ISO standards
Community Surface Dynamics Modeling System. The Community Surface Dynamics Modeling System (CSDMS) deals with the Earth's surface and the observable and projected changes constantly taking place – the ever-changing dynamic interface between lithosphere, hydrosphere, cryosphere and atmosphere.

CSDMS supports the development, integration, dissemination and archiving of community open-source software, that reflects and predicts earth-surface processes over a broad range of temporal and spatial scales.

Over 500 research institutions from more than 65 countries comprise the community effort. CSDMS distributes hundreds of open-source models and modeling tools, provides access to high performance computing clusters in support of developing and running earth surface models, and offers a suite of products for education and knowledge transfer.

The CSDMS architecture employs frameworks and services that convert stand-alone models into flexible "plug-and-play" components to be assembled into larger applications.   CSDMS focuses on the movement of fluids and the sediment and solutes they transport through landscapes, seascapes and sedimentary basins.  Began in 2007 under the leadership of James Syvitski, formerly the director of the Institute of Arctic and Alpine Research (INSTAAR), Boulder, CO, CSDMS operates under continuing funding from the National Science Foundation (NSF) to coordinate this national effort related to surface dynamic modeling.

References

External links
 NSF Award page

Geology organizations
Earth science research institutes
Geomorphology
Earth sciences
Sedimentology
International scientific organizations
International organizations based in the United States
European Committee for Interoperable Systems. The European Committee for Interoperable Systems (ECIS) is an international non-profit association founded in 1989 in order to promote interoperability and market conditions in the Information and Communications Technology (ICT) sector allowing vigorous competition on the merits and a diversity of consumer choice. ECIS has represented its members on many issues related to interoperability and competition before European, national and international bodies, including the European Union institutions and the World Intellectual Property Organization (WIPO).  ECIS members include large and smaller information and communications technology hardware and software providers as Adobe Systems, Corel Corporation, IBM, Linspire, Nokia, Opera Software, Oracle Corporation, RealNetworks, Red Hat, and Sun Microsystems.

Involvement against Microsoft dominance
Over the past years, ECIS has been actively involved in the European Commission's antitrust condemnation against Microsoft, now upheld by the European Court of First Instance in September 2007.

Ziff-Davis' eWeek comments that  - 

Other complaints about Microsoft include:
 That bundling XAML in Vista is an attempt to replace HTML by a Microsoft-specific technology
 That Office Open XML is a Microsoft-dependent document format

See also
Free Software Foundation Europe
OpenForum Europe

Statements about the European Commission's antitrust case against Microsoft
ECIS statement from Oct. 22 on the EU-MS agreement
ECIS statement on the European Court First Instance (CFI) Microsoft judgment
March 26, 2004 ECIS welcomes Commission Decision finding Microsoft infringed Article 82

References

External links
 ECIS main site

Information technology organizations based in Europe
Interoperability
Standards organisations in Belgium
The Big Electric Cat. The Big Electric Cat, named for an Adrian Belew song, was a public access computer system in New York City in the late 1980s, known on Usenet as node dasys1.

Based on a Stride Computer brand minicomputer running the UniStride Unix variant, the Big Electric Cat (sometimes known as BEC) provided dialup modem users with text terminal-based access to Usenet at no charge.

This was the first such system in New York and one of the first in the world. Previously, access to Usenet had been almost exclusively through systems at universities, or a few government and very few commercial installations. While Bulletin Board System culture and Fidonet existed at the time, systems which allowed the general public to access Usenet were virtually unknown. As with many early Internet and Usenet systems, a community began to form among users of the system which had occasional outings to restaurants.

History
BEC was started by four college students, with one of them, Rob Sweeney, owning the equipment. The other sysops were Charles Foreman, Lee Fischman, and Richard Newman.

A list of BBSes in the 212 Area Code contains the following note, attributed to Lee Fischman
I was one of the sysops. Originally we were set up (illicitly) in the computer room of a midtown advertising agency. It is a VERY amusing story -- pity you didn't know about it before the movie! We eventually migrated to the offices of a communications firm elsewhere in the city. I still have the Big Electric Cat user manual, with its very entertaining cover. Robert Sweeney was killed in a motorcycle accident in 2001.
The movie referred to is BBS: The Documentary.

BEC was not intended to be a profit-making operation, charging fees that were designed only to cover operating costs, (Phrack reports $5 per month for an account at the end of 1989, though the system may have in fact been out of operation by then, and other sources note that the system was supported by donations) and relying entirely on volunteer labor.

In mid-1990, after increasingly unreliable operation, The Big Electric Cat suffered what proved to be fatal hardware failure, leaving a gap which was filled by some its users founding one of the first commercial ISPs ever, Panix.

2600 Magazine founder Eric Corley used a Big Electric Cat account.

References

Panix (ISP)
History of the Internet
Shell account providers
Stereoscopic rangefinder. A stereoscopic rangefinder or stereoscopic telemeter is an optical device that measures distance from the observer to a target, using the observer's capability of binocular vision. It looks similar to a coincidence rangefinder, which uses different principles and has only one eyepiece. German instruments tended to use the stereoscopic principle while British ones used coincidence.

Technical principle
A stereoscopic rangefinder uses two eyepieces and relies on the operator's visual cortex to merge the two images into a single picture. A reference mark is separately inserted into each eyepiece.  The operator first adjusts the direction of the range finder so that the fixed mark is centered on the target, and then the prisms are rotated until the mark appears to overlap in the operator's combined view. The range to the target is proportional to the degree of rotation of the prisms.

Coincidence vs stereoscopic rangefinders
In November and December 1941, the United States National Defense Research Committee conducted extensive tests between the American Bausch and Lomb M1 stereoscopic rangefinder and the British Barr and Stroud FQ 25 and UB 7 coincidence rangefinders, and concluded "that the tests indicate no important difference in the precision obtainable from the two types of instrument – coincidence and stereoscopic. They do indicate, however, that the difference in performance between large and small instruments is by no means as great as would be anticipated from simple geometrical optics. The report concludes with the belief that stereoscopic and coincidence acuities are about equal. Under favourable conditions existing instruments of the two types perform about equally well, and the choice between them for any given purpose must be based on matters of convenience related to the particular conditions under which they are to be used."

Height finder
The angle of sight of a rangefinder and the range to the target can be combined in a simple computer to produce a measurement of altitude. The resulting instrument becomes a combined height-finder/rangefinder and was standard equipment for land and naval based anti-aircraft units. The stereoscopic rangefinder was preferred to coincidence rangefinders for anti-aircraft artillery because small, fast moving objects in front of a low-contrast sky could easily be tracked.

See also
Stadiametric rangefinding
Coincidence rangefinder
Rangefinder
Telemeter

References

Length, distance, or range measuring devices
Anti-aircraft artillery
Firearm sights
Micromanipulator. A micromanipulator is a device which is used to physically interact with a sample under a microscope, where a level of precision of movement is necessary that cannot be achieved by the unaided human hand. It may typically consist of an input joystick, a mechanism for reducing the range of movement and an output section with the means of holding a microtool to hold, inject, cut or otherwise manipulate the object as required. The mechanism for reducing the movement usually requires the movement to be free of backlash. This is achieved by the use of kinematic constraints to allow each part of the mechanism to move only in one or more chosen degrees of freedom, which achieves a high precision and repeatability of movement, usually at the expense of some absolute accuracy.

Movement

Movement reduction can be performed by mechanical levers, hydraulically using pistons of different diameters connected by tubing containing non-compressible fluid,  electronically using stepper motors or linear actuators, or combinations of techniques in one instrument. Mechanisms with different ranges of movement or variable reduction ratio may be incorporated in one instrument to allow coarse and fine positioning.

Depending on the application, users may require different scales of movement resolution, movement speed, range and accuracy. These are the critical variables integrated into manipulator design by manufacturers, which are typically presented to suit particular applications.

Microscope integration
Micromanipulators are usually used in conjunction with microscopes.  Depending on the application, one or more micromanipulators may be fitted to a microscope stage or rigidly mounted to a bench next to a microscope.  A typical application of micromanipulation is human intracytoplasmic sperm injection. Here, a spermatozoon measuring some 3 to 5 micrometres across is injected into an oocyte of approximately 100 micrometres in diameter, under the direct manual control of an embryologist. A disposable glass micropipette is fitted to a toolholder mounted on the output of the manipulator. The toolholder can be adjusted for different sized tools as well as the angle at which the tool is held.

Microelectronics
Micromanipulators are also used in applications such as microelectronics to position test probes onto small to medium scale integrated circuits and hybrid devices, and patch clamp experiments in biological research.

References

Further reading

 Robert Barer, A. E. Saunders-Singer. A New Single-control Micromanipulator 
 V. B. D. Skerman A New Type of Micromanipulator and Microforge J. gen. Microbiol. (1968), 54, 287-297
 Fred Sherman Micromanipulator for Yeast Genetic Studies Applied Microbiology, Nov. 1973, p. 829
 Inventors: Fonbrune, Pierre Henry Dussu DE.; Andre, Beaudouin Paul Micromanipulator controller U.S. Patent 2988928 
 Inventors: Rowland, May Kenneth Micromanipulating devices U.S. Patent 2800055  (1957)
 Inventors: Karl, Frischmann Micromanipulator U.S. Patent 2760405 
 Fundamentals Series: Micromanipulators Part 2 

Positioning instruments
Scientific equipment
Maneuvering speed. In aviation, the maneuvering speed of an aircraft is an airspeed limitation at which the full deflection of the controls can be made at without risking structural damage.

The maneuvering speed of an aircraft is shown on a cockpit placard and in the aircraft's flight manual but is not commonly shown on the aircraft's airspeed indicator.

In the context of air combat maneuvering (ACM), the maneuvering speed is also known as corner speed or cornering speed.

Implications

It has been widely misunderstood that flight below maneuvering speed will provide total protection from structural failure. In response to the destruction of American Airlines Flight 587, a CFR Final Rule was issued clarifying that "flying at or below the design maneuvering speed does not allow a pilot to make multiple large control inputs in one airplane axis or single full control inputs in more than one airplane axis at a time". Such actions "may result in structural failures at any speed, including below the maneuvering speed."

Design maneuvering speed VA
VA is the design maneuvering speed and is a calibrated airspeed.  Maneuvering speed cannot be slower than  and need not be greater than Vc.

If  is chosen by the manufacturer to be exactly  the aircraft will stall in a nose-up pitching maneuver before the structure is subjected to its limiting aerodynamic load.  However, if  is selected to be greater than , the structure will be subjected to loads which exceed the limiting load unless the pilot checks the maneuver.

The maneuvering speed or maximum operating maneuvering speed depicted on a cockpit placard is calculated for the maximum weight of the aircraft.  Some Pilot's Operating Handbooks also present safe speeds for weights less than the maximum.

The formula used to calculate a safe speed for a lower weight is , where VA is maneuvering speed (at maximum weight), W2 is actual weight, W1 is maximum weight.

Maximum operating maneuvering speed VO
Some aircraft have a maximum operating maneuvering speed VO.  Note that this is a different concept than design maneuvering speed.  The concept of maximum operating maneuvering speed was introduced to the US type-certification standards for light aircraft in 1993. The maximum operating maneuvering speed is selected by the aircraft designer and cannot be more than , where Vs is the stalling speed of the aircraft, and n is the maximal allowed positive load factor.

See also 
 V speeds
 American Airlines Flight 587

References

External links 
  "Design airspeeds"

Airspeed
Aerodynamics
Pont de la Tournelle. The  (, Tournelle Bridge), is an arch bridge spanning the river Seine in Paris.

History
The location of the  is the site of successive structures.

The first, a wooden bridge, was built in 1620. This bridge connected the Eastern bank of the Seine (le quai Saint-Bernard) to . It was subsequently washed away by ice in 1637, and again on 21 January 1651. A stone bridge was erected in its place in 1654. It was demolished in 1918 and replaced by the current bridge in 1928, after it suffered several natural disasters, especially the flood of 1910.

The  was intentionally built lacking symmetry, in order to emphasize the shapeless landscape in the part of the Seine that it bestrides. Consisting of a grand central arch that links the riverbanks via two smaller arches, one on each side, it's decorated on the Eastern bank with a pylon built on the left pier's cutwater, and a statue of Saint Geneviève, the patron saint of Paris, atop of the pylon, designed by Polish-French monumental sculptor Paul Landowski.

The term "Tournelle" traces its origin to a square turret () constructed at the end of the 12th Century on the fortress of Phillipe Auguste.

Numerous scenes of Highlander: The Series were filmed along the Quai de la Tournelle near and underneath Pont de la Tournelle between 1992 and 1998.

Access

See also 
 List of crossings of the River Seine

References

External links

  Bridge history
  More bridge history

Bridges over the River Seine in Paris
Bridges completed in the 17th century
Buildings and structures completed in 1658
Transport infrastructure completed in the 1650s
Bridges completed in 1928
Buildings and structures in the 4th arrondissement of Paris
1658 establishments in France