omniomni/omni-engineering huggingface dataset:
Carrier-sense multiple access with collision avoidance and resolution using priorities. In computer networking, carrier-sense multiple access with collision avoidance and resolution using priorities (CSMA/CARP) is a channel access method. CSMA/CARP is similar in nature to the carrier-sense multiple access with collision detection (CSMA/CD) channel access method used in Ethernet networks, but CSMA/CARP provides no detection of network collisions.  Instead of detecting network collisions, CSMA/CARP attempts to avoid collisions by using a system of transmission priorities.

When a station wants to transmit on a CSMA/CARP network it first listens for network traffic and if the medium is clear instead of immediately transmitting as a station would in CSMA/CD it waits a predefined amount of time.   This waiting period is called the interframe spacing (IFS) and it varies by the type of data being transmitted.   High priority data will transmit almost immediately whereas lower priority data such as polling will have a longer IFS.  This system allows CSMA/CARP to avoid many collisions that would occur if it was not used. In addition to having a different IFS per priority, a station in a CSMA/CARP network will add a "random backoff" to its waiting period, to reduce the collision probability between stations that have to transmit packets in the same priority.

Applications 
 The IEEE 802.11 standard uses CSMA/CARP
 The ITU-T G.hn standard, which provides high-speed local area networking over existing home wiring (power lines, phone lines and coaxial cables) includes support for CSMA/CARP, although only during certain periods of time called "Shared Transmission Opportunities" (STXOP). During the rest of the time, G.hn uses a time-division multiple access channel access method to ensure quality of service.

Channel access methods
Man-Machine. Man-Machine or Man and Machine may refer to:

Technology 

 Human–computer interaction, man-machine interaction (MMI)
 MML (programming language), a man-machine language
 Cyborg, a cybernetic organism which enhances its abilities by using technology
 Transhumanism, the idea of human enhancement via technology

Music 

 The Man-Machine, a 1978 album by Kraftwerk
 Man vs. Machine, a 2002 album by rapper Xzibit
 Man and Machine (album), a 2002 album by U.D.O.
 Man Machine, an early '90s techno/electro project, signed to Rhythm King

Other 

 Machine Man, a 1977 character created by Jack Kirby for Marvel Comics
 Mann & Machine, a 1992 American science fiction police drama television series
 Ghost in the Shell 2: Man-Machine Interface, a 1997 manga by Masamune Shirow
 Man a Machine, a 1748 work of materialist philosophy by French physician and philosopher Julien Offray de La Mettrie
 Maschinenmensch ("machine-human"), a robot featured in the film Metropolis

See also 
 Man engine, a ladder-like mechanism installed in mines
SNAPI. SNAPI is a system that allows a visually impaired user to record their preferences onto a smart card or other security token.

When a card, mobile phone, key fob token or similar portable object containing SNAPI data is put into public or shared IT equipment, or moved into the field of the equipment's sensor, it informs the terminal about the user's preferred user interface. The terminal could be a shared personal computer, a public kiosk, a ticket machine, a turnstile or an automated teller machine (ATM). This can enable various accessibility modes such as a high-contrast display or increased typeface size, audible prompts, or increased time for responses for the duration of the transaction. When the transaction is complete, the terminal returns to its default settings.

The coding is specified in the European standard EN 1332–4. The Local Authority Smartcard Standards e-Organisation (LASSeO) has supported the inclusion of SNAPI coding in various UK local authority smart card schemes.

References

Application programming interfaces
Accessibility
Accessible information
Assistive technology

External links
Isambard Brunel. Isambard Brunel may refer to individuals from three generations of the engineering dynasty:

 Sir Marc Isambard Brunel (1769–1849), French-born engineer who settled in England
 Isambard Kingdom Brunel (1806–1859), English mechanical and civil engineer
 Isambard Brunel Junior (1837–1902), son of Isambard Kingdom Brunel

See also 
 Isambard
Banert cascade. The Banert cascade is an organic reaction in which an NH-1,2,3-triazole is prepared from a propargyl halide or sulfate and sodium azide in a dioxane- water mixture at elevated temperatures. It is named after Klaus Banert, who first reported the process in 1989. This cascade reaction is unusual because it consists of two consecutive rearrangement reactions.

The starting material is prepared from propargyl chloride and an aldehyde or ketone such as acetaldehyde. In the first step an azido compound is formed in situ in a nucleophilic displacement of chloride by the azide ion. A (3,3)Sigmatropic reaction takes place between the azide and the alkyne to the allenyl azide. This allene rearranges to the triazafulvene in a 6 pi electrocyclization. The exocyclic alkene in this intermediate is very electrophilic because the triazole group has a dipole moment of 5 debye. The reaction sequence concludes with nucleophilic attack of a second azide ion on this alkene with more double bond rearrangements and proton abstraction from a proton source.

References 

Heterocycle forming reactions
Rearrangement reactions
Name reactions
Drag freight. A drag freight is a long, slow, high-tonnage railroad train, often carrying commodities such as coal or ore. Compared to "fast freight" trains, drag freight trains have a very low power-to-weight ratio, making them somewhat unpredictable on steep grades or hilly routes. This causes many dispatchers to be extremely conservative with how they handle drag freights, especially when they share lines with higher priority fast freights and passenger trains.

Power 

Before and during WWI and into the 1920s, large locomotives such as the 2-8-2 Mikado or mainly larger types like Articulated locomotives were typically used for drag freight operations.

After the railroads dieselized, heavy duty diesel locomotives (typically six-axle units, to improve adhesion) were used for the drag freights. Multiple unit operations allowed one person to control multiple locomotives. As many as 4 to 11 locomotives may be used for a heavy haul drag freight. Attempts were made to develop ultra-large locomotives for this purpose, such as the Union Pacific DDA40X and gas-turbine locomotives.

When AC traction motors and thyristor inverters became available, locomotives such as EMD SD70MAC and the GE AC4400CW replaced the older EMD SD40 on a three-for-two basis.

United Kingdom

In the UK, such trains were called mineral trains and the locomotives that hauled them were called mineral locomotives. An example of a mineral locomotive was the LNWR 17in Coal Engine.

The trains were loose-coupled, had no continuous brakes, and were speed-limited to . The lack of brake power was a potential hazard and, when approaching a downhill gradient, it was necessary to stop the train and "pin down" the handbrakes on some of the wagons before proceeding.

Today, Class 60 and Class 66 locomotives owned by the DB Cargo UK and Freightliner Heavy Haul are used for drag freights. Also, Class 59 locomotives owned by National Power, Foster Yeoman, and other large bulk shippers were used on the heavy freights in the 1990s. Because of coupling limits, only single units were used.

External links

Trains
Boeing 367. Boeing 367 was a model number for aircraft within the Boeing Company and refers to two different aircraft:

Boeing 367/C-97 Stratofreighter was a B-29 based prototype for the Boeing 377 Stratocruiser aircraft.
Boeing 367-80 or 'Dash 80', the 1950s prototype of Boeing's first jet airliner which had evolved from the original 367 design through a large number of design studies.
Zinc selenide. Zinc selenide is the inorganic compound with the formula ZnSe.  It is a lemon-yellow solid although most samples have a duller color due to the effects of oxidation. It is an intrinsic semiconductor with a band gap of about 2.70 eV at , equivalent to a wavelength of 459 nm. ZnSe occurs as the rare mineral stilleite, named after Hans Stille.

Synthesis and properties
ZnSe is available in both hexagonal (wurtzite) and cubic (zincblende) polymorphs.  In both cases, the Zn2+ and Se2− sites are tetrahedral.  The difference in the structures related to close packing motifs, hexagonal vs cubic.

Cubic ZnSe is produced by treatment of an aqueous solution of zinc sulfate with hydrogen selenide:

Heating the cubic form gives hexagonal ZnSe.

An alternative synthesis involves heating a mixture of zinc oxide, zinc sulfide, and selenium:

It is a wide-bandgap semiconductor of the  II-VI semiconductor group (since zinc and selenium belong to the 12th and 16th groups of the periodic table, respectively). The material can be n-type doped with, for instance, halogen elements. P-type doping is more difficult, but can be achieved by introducing gallium.

Applications
 ZnSe is used to form II-VI light-emitting diodes and diode lasers. It emits blue light.
 ZnSe doped with chromium (ZnSe:Cr) has been used as an infrared laser gain medium emitting at about 2.4 μm.
 It is used as an infrared optical material with a remarkably wide transmission wavelength range (0.45 μm to 21.5 μm). The refractive index is about 2.67 at 550 nm (green), and about 2.40 at 10.6 μm (LWIR). Similar to zinc sulfide, ZnSe is produced as microcrystalline sheets by synthesis from hydrogen selenide gas and zinc vapour. Another method of producing is a growth from melt under excessive pressure of inert gas (Ar usually). When free of absorption and inclusions it is ideally suited for CO2 laser optics at 10.6 μm wavelength. It is thus a very important IR material. In daily life, it can be found as the entrance optic in the new range of "in-ear" clinical thermometers, seen as a small yellow window. Zinc selenide can slowly react with atmospheric moisture if poorly polished, but this is not generally a serious problem. Except where optics are used in spectroscopy or at the Brewster angle, antireflection or beamsplitting optical coatings are generally employed.
 ZnSe activated with tellurium (ZnSe(Te)) is a scintillator with emission peak at 640 nm, suitable for matching with photodiodes. It is used in x-ray and gamma ray detectors. ZnSe scintillators are significantly different from the ZnS ones.

Reactions
ZnSe is insoluble in water, but dissolves in concentrated hydrochloric acid.

It can be deposited as a thin film by chemical vapour deposition techniques including MOVPE and vacuum evaporation.

References

External links
Coherent Optical Data optical data & more

selenide
Selenides
II-VI semiconductors
Optical materials
Phosphors and scintillators
Laser gain media
Zincblende crystal structure
Wurtzite structure type
*Lisp. *Lisp (or StarLisp) is a programming language, a dialect of the language Lisp. It was conceived of in 1985 by two employees of the Thinking Machines Corporation, Cliff Lasser and Steve Omohundro, as a way to provide an efficient yet high-level language for programming the nascent Connection Machine (CM).

History

Prelude
At the time the Connection Machine was being designed and built, the only language being actively developed for it was an assembly-level language named PARIS (Parallel Instruction Set). It became evident that a better way to program the machine was needed, and quickly. Waiting for the completion of Connection Machine Lisp (CM Lisp), an implementation of the very high-level programming language Lisp with parallel computing extensions) was not an option. CM Lisp had been proposed by Danny Hillis, and development was expected to continue for several more years.

Development
A *Lisp interpreter was initially developed. It became apparent quickly that a *Lisp compiler, translating *Lisp into Lisp and PARIS, would be needed to attain the gigaFLOPS speed that was attainable in theory by a Connection Machine. The *Lisp compiler was written by Jeff Mincy and was first released in 1986. An application achieving more than two gigaFLOPS, a helicopter wake simulator, was developed by Alan Egolf, then an employee of United Technologies, and J. P. Massar, a Thinking Machines employee, in 1987.

A *Lisp Simulator, an emulator meant to run *Lisp code on standard, non-parallel machines, was developed at the same time by J. P. Massar. This simulator still exists, and was ported to American National Standards Institute (ANSI) Common Lisp (CL) in 2001. An older version written in the original CL, exists in the Carnegie Mellon University (CMU) artificial intelligence (AI) repository.

Later versions of *Lisp, involving significant upgrades to its functions and performance, were worked on by Cliff Lasser, Jeff Mincy, and J. P. Massar through 1989. *Lisp was implemented on the Thinking Machines CM5 circa 1990–1991 by J. P. Massar and Mario Bourgoin.

Implementation
StarLisp was written on Common Lisp (CL), and thus had the full power of CL behind it. To use a Connection Machine, one needed a host or front-end. To use *Lisp, that front-end had to run CL. Symbolics' machines using Genera and Sun Microsystems workstations running Lucid Inc.'s Lucid Common Lisp were both used to operate *Lisp.

StarLisp operated on Parallel Variables (PVARS). These represented Connection Machine memory, and were essentially vectors: one element per CM processor (or virtual processor).

StarLisp consisted of standard operations on PVARS, like vector addition and multiplication, along with communication primitives that essentially reordered the elements of a PVAR using the CM's communication hardware to optimally route the data.

References

Concurrent programming languages
Dynamically typed programming languages
Functional languages
Lisp programming language family
Common Lisp (programming language) software
Multi-paradigm programming languages
Bondo (putty). Bondo is a polyester putty product originally marketed as an automotive body filler. Nowadays the brand name is used by 3M for a line of American-made products for automotive, marine and household repairs. The term Bondo is trademarked by 3M, but is commonly used to refer to any brand of automotive repair putty due to its popularity. It is also used by sculptors.

History

Before the 1950s, body solder was often used to repair large imperfections prior to painting in both new cars and vehicle repair shops. Solder repairs were conducted using a flame and wooden paddles covered in tallow or motor oil, which prevented the half-molten lead from sticking.

After World War II, automotive panels became thinner and larger, with a greater susceptibility to warping, making hot solder unsuitable. The earliest 'plastic solder' can be traced to around 1940, a do-it-yourself solution to panel beating.
This gave the consumer the ability to attempt reasonably priced and long lasting repairs. These early fillers were epoxy-based and one-part, drying by outgassing. Originally, the plastic fillers performed badly compared to solder, but later improvements addressed this.

Bondo, a two-part mix (resin with hardener added) of talc and plastic, was introduced in 1955. It was developed by WWII veteran and automotive repair shop owner Robert Merton Spink of Miami, Florida. Bondo was acquired by 3M in 2007.

References

External links
 

3M brands
Brand name materials
Automotive technologies
Polyesters
Chris Mack (scientist). Chris Mack (born c. 1960) is an expert in photolithography. He received multiple undergraduate degrees from Rose-Hulman Institute of Technology in 1982, a master of science degree in electrical engineering from the University of Maryland, College Park in 1989, and a PhD in chemical engineering from The University of Texas in 1998.

He became acquainted with lithography while working at the Microelectronics Research Laboratory of the NSA. After an assignment to Sematech, he quit his job at the NSA and founded FINLE Technologies (1990) to commercialize PROLITH, the simulator he had developed to model optical and chemical aspects of photolithography. FINLE Technologies was purchased in February 2000 by KLA-Tencor, which now markets PROLITH. 

In 2017, he cofounded Fractilia, Inc. to deliver MetroLER, a software product that models stochastic effects in the semiconductor manufacturing process. He currently serves as CTO of Fractilia.

He is currently an adjunct faculty member at The University of Texas at Austin. He writes a quarterly column called the Lithography Expert.

In 2003 he received the Semiconductor Equipment and Materials International SEMI Award for North America.  In 2005, he was the subject of the first annual Chris Mack Roast at the SPIE Microlithography conference. In 2009, Mack was awarded the Frits Zernike Award for Microlithography at the SPIE Advanced Lithography Symposium.

References

External links
Chris Mack's personal website
PROLITH at KLA-Tencor 
Fractilia

Living people
1960s births
Rose–Hulman Institute of Technology alumni
University of Maryland, College Park alumni
Cockrell School of Engineering alumni
University of Texas at Austin faculty
American scientists
SPIE
Nisil. Nisil is an alloy of nickel (95.5% wt.) and silicon (4.4% wt.) with traces of Mg (0.1% wt.), which is non-magnetic.

Nisil melts at 1341 - 1420 °C, has a density of 8.58 g/cm3, and electrical resistivity of 0.365 Ω⋅mm2/m at 20 °C.

It is often used in conjunction with Nicrosil in type N thermocouples. In this use, it serves as the negative leg of the thermocouple. It offers higher thermoelectric stability in air above 1000°C (1830°F) and better oxidation resistance than type E, J and K thermocouples. It can not be exposed to sulphur-containing gases.

External links
  Materials properties of thermocouple wires sold by Omega Engineering, Inc. 
 Thermocouples properties by Thermometrics.
 Properties of Nisil

Nickel alloys
Silicon alloys
Refractory metals
Vickers 131 Valiant. The Vickers Type 131 Valiant was a British general-purpose biplane produced by Vickers in 1927, with the intention of replacing the Royal Air Force's Airco DH.9As, but was unsuccessful, with only a single example built, which was sold to Chile.

Development and design

In 1926, based on experience with the wooden-winged Vickers Vixen biplane, where the wings proved vulnerable to extremes of temperature and humidity, designed a set of metal wings for the Vixen, with which it became the Vickers Vivid, and in parallel, designed an all-metal general purpose biplane, the Vickers Type 131, hoping to replace the DH.9A in that role. In 1927, the British Air Ministry issued Specification 26/27 for a DH.9A replacement which, to save money, had to use as many components of the DH.9A as possible because the RAF held large stocks of DH.9A spares. Vickers submitted the Type 131 design to the Ministry but, as it did not make use of the required DH9A components, did not receive a contract for a prototype. However Vickers decided to build a single prototype as a private venture for evaluation against the specification.

The Vickers 131 Valiant was a single-bay biplane of all-metal construction, sharing much of the structure with the Vivid. It was powered by a 492 hp (367 kW) Bristol Jupiter engine, and the crew of two sat in separate but adjacent cockpits, giving good communication between the pilot and observer. It could carry up to 500 lb (230 kg) of bombs under the wing, with a fixed Vickers machine gun for the pilot and a Lewis gun on a Scarff ring for the observer.

The prototype had made its first flight by 5 March 1927, and underwent official evaluation against the designs from Bristol (the Beaver), Fairey (the Fairey Ferret and IIIF), Gloster (the Goral) and Westland (the Wapiti). Its initial tests showed it to possess good handling, and was taken forwards for squadron trials, along with the Ferret, IIIF and Wapiti. Following these trials, the Wapiti was chosen as the winner, with the Valiant, which was 30% more expensive than the Wapiti, rejected because it was a poor bombing platform, not being sufficiently stable.

Operational history
The Valiant was shipped to Chile in 1928 for demonstration to the Chilean Air Force that wanted a replacement for their Vixens. While no production followed, Chile purchased the prototype, which entered service with the School of Aviation, being destroyed in a crash on 29 March 1929.

Operators

Chilean Air Force

Specifications (Type 131 Valiant)

See also

References

Notes

Bibliography

1920s British bomber aircraft
1920s British military reconnaissance aircraft
131 Valiant
Single-engined tractor aircraft
Biplanes
Aircraft first flown in 1927
Aircraft with fixed conventional landing gear
Crystallinity. Crystallinity refers to the degree of structural order in a solid. In a crystal, the atoms or molecules are arranged in a regular, periodic manner. The degree of crystallinity has a large influence on hardness, density, transparency and diffusion. In an ideal gas, the relative positions of the atoms or molecules are completely random. Amorphous materials, such as liquids and glasses, represent an intermediate case, having order over short distances (a few atomic or molecular spacings) but not over longer distances.

Many materials, such as glass-ceramics and some polymers, can be prepared in such a way as to produce a mixture of crystalline and amorphous regions. In such cases, crystallinity is usually specified as a percentage of the volume of the material that is crystalline. Even within materials that are completely crystalline, however, the degree of structural perfection can vary. For instance, most metallic alloys are crystalline, but they usually comprise many independent crystalline regions (grains or crystallites) in various orientations separated by grain boundaries; furthermore, they contain other crystallographic defects (notably dislocations) that reduce the degree of structural perfection. The most highly perfect crystals are silicon boules produced for semiconductor electronics; these are large single crystals (so they have no grain boundaries), are nearly free of dislocations, and have precisely controlled concentrations of defect atoms.

Crystallinity can be measured using x-ray diffraction, but calorimetric techniques are also commonly used.

Rock crystallinity 
Geologists describe four qualitative levels of crystallinity:
 holocrystalline rocks are completely crystalline;
 hypocrystalline rocks are partially crystalline, with crystals embedded in an amorphous or glassy matrix;
 hypohyaline rocks are partially glassy;
 holohyaline rocks (such as obsidian) are completely glassy.

References
Oxford dictionary of science, 1999, .

Crystals
Physical quantities      
Phases of matter