omniomni/omni-engineering huggingface dataset:
Midnight Engineering. Midnight Engineering was a bimonthly magazine that was published by William E. "Bill" Gates (not to be confused with William Henry Gates III, the founder of Microsoft), from December 1989 to 2001. The first issue appeared in January/February 1990. The target audience was primarily hardware and software engineers running their own small businesses or holding "day jobs" and "burning the midnight oil" developing products or services to allow them to become independent entrepreneurs. The headquarters was in Rocky Ford, Colorado.

There is still a conference associated with readers of the magazine, initially called ME SKI in 1992, renamed to ENTCON (Entrepreneurs Conference) shortly thereafter, and transformed into EntConnect in 2003.  It is still held early each Spring in Denver, Colorado, and attended most years by the magazine's founder, Bill Gates.

References

External links
EntConnect Entrepreneurial Connections Conference

Bimonthly magazines published in the United States
Defunct computer magazines published in the United States
Engineering magazines
Magazines established in 1989
Magazines disestablished in 2001
Magazines published in Colorado
Barking dog reaction. The "Barking Dog" is an exothermic chemical reaction that results from the ignition of a mixture of carbon disulfide and nitrous oxide. When ignited in a cylindrical tube, the reaction produces a bright flash and a loud "woof" - reminiscent of a barking dog.

In simple terms, the 'Barking Dog' reaction is a combustion process, in which a fuel (carbon disulfide, CS2) reacts with an oxidizing agent (nitrous oxide, N2O), producing heat and elemental sulfur.  The flame front in the reaction is a zone of very hot, luminous gas, produced by the reactants decomposing.

8 N2O + 4 CS2 → S8 + 4 CO2 + 8 N2

In April 1853, Justus von Liebig performed the demonstration in front of the Bavarian royal family; however, the glass container shattered, and shards of glass inflicted minor injuries on the faces of Queen Therese, her son Prince Luitpold, and Liebig himself.

References

External links
 Barking Dog (slow motion) - Periodic Table of Videos, University of Nottingham
 University of Leeds Barking Dog site 
   Elementary Productions: Small scale Barking Dog reaction @  youtube
  Barking Dog Reaction How to Do the Barking Dog Chemistry Demonstration 

Chemical reactions
Chemistry classroom experiments
Articles containing video clips
Taraba River. The Taraba River is a river in Taraba State, Nigeria, a tributary of the Benue River. It joins the Benue on a floodplain 10 km wide and 50 km across.

The major towns along the River Taraba are Sert-Baruwa, Sarki Ruwa, Karamti, Jamtari, Gangumi, Gayam and Bali LGA. The major economic activities on the river are fishing, farming of rice, yam and groundnut.

The major ethnic groups inhabiting the river are the Fulani and the Chamba.

Pollution
The governor of Taraba State, Agbu Kefas ordered the suspension of all mining activities to protect the environment and promote sustainable growth because the increase in mining activity in the state resulted in deforestation, water pollution, and a loss of biodiversity.

References 

Benue River
Proactive maintenance. Proactive maintenance is the maintenance philosophy that supplants “failure reactive” with “failure proactive” by activities that avoid the underlying conditions that lead to machine faults and degradation.  Unlike predictive or preventive maintenance, proactive maintenance commissions corrective actions aimed at failure root causes, not failure symptoms.  Its central theme is to extend the life of machinery as opposed to
making repairs when often nothing is wrong,
accommodating failure as routine or normal, or
detecting impending failure conditions followed by remediation.
Proactive maintenance depends on rigorous machine inspection and condition monitoring.  In mechanical machinery it seeks to detect and eradicate failure root causes such as wrong lubricant, degraded lubricant, contaminated lubricant, botched repair, misalignment, unbalance and operator error.

See also
 Predictive maintenance

References

Mechanical engineering
Maintenance
Argonaut class reactor. The Argonaut class reactor is a design of small nuclear research reactor. Many have been built throughout the world, over a wide range of power levels. Its functions are to teach nuclear reactor theory, nuclear physics and for use in engineering laboratory experiments.

Description 
The original Argonaut (Argonne Nuclear Assembly for University Training) was built at Argonne National Laboratory and went critical for the first time on February 9, 1957. It was shut down in 1972. This reactor was rated for 10 kilowatts.

See also 

 UF Training Reactor
 More Hall Annex

Citations

References

Further reading 

 

 
Argonne National Laboratory
Lead(II) chloride (data page). This page provides supplementary chemical data on lead(II) chloride.

Structure and properties

Thermodynamic properties

Spectral data

Regulatory data

Material Safety Data Sheet  

The handling of this chemical may incur notable safety precautions. It is highly recommend that you seek the Material Safety Datasheet (MSDS) for this chemical from a reliable source  such as SIRI, and follow its directions.

References

Chemical data pages
Chemical data pages cleanup
Lambda transition. The λ (lambda) universality class is a group in condensed matter physics. It regroups several systems possessing strong analogies, namely, superfluids, superconductors and smectics (liquid crystals). All these systems are expected to belong to the same universality class for the thermodynamic critical properties of the phase transition.  While these systems are quite different at the first glance, they all are described by similar formalisms and their typical phase diagrams are identical.

See also 
 Superfluid
 Superconductor
 Liquid crystal
 Phase transition
 Renormalization group
 Topological defect

References

Books 

 Chaikin P. M. and Lubensky T. C. Principles of Condensed Matter Physics (Cambridge University Press, Cambridge) 1995, sect.9.
 Feynman R. P. Progress in Low Temperature Physics Vol.1, edited by C. Gorter (North Holland, Amsterdam) 1955.

Journal articles 

 
 
 
 
 
 
  Translated as: 
 

Condensed matter physics
Critical phenomena
Phase transitions
Phases of matter
Poly-cap. A poly-cap is a small rubber polyethylene bushing used to create smooth joints, or to keep something in place without glue in scale-models. In model kit descriptions, they are sometimes referred to under the material acronym PE. They are usually found on kits such as those by Tamiya and Bandai who have employed them for a long time. 

Although regarded as a quick and reliable solution to create stiff joints to hold poses, they have shown to deteriorate in strength if too much friction is applied from shifting poses, as well as a loss in grip strength over the course of a few years without tampering, causing the final build to be unable to hold more complex poses over time. As such, manufactures such as Bandai have shown signs of abandonment in more recent releases of the part in favor of more solid, peg reliant engineering, and using harder plastics to keep poses held, although the material is still used in re-releases of old kits.

A typical "cap" is a small cylinder, but many other shapes exist. Bandai for example have a wide range of designs used in their mecha model kits (Gunpla, etc.). 

Typical uses include
 Wheel or sprocket-hubs
 Pivot-points for guns
 Joints in robotic limbs

Hardware (mechanical)
AGM-87 Focus. The AGM-87 Focus was an air-to-surface missile developed by the United States.

Overview

The missile was a development of the AIM-9B Sidewinder air-to-air missile, intended for use against ground targets. Development took place at the China Lake Naval Weapons Center during the late 1960s. The infrared homing method of the Sidewinder was retained, as the missile was to be used against targets which emitted an infrared signature. Typical targets included trucks and other such vehicles.

The Focus was used in Vietnam during 1969 and 1970, primarily for night attacks when IR emitters stand out well against the cool background. Although the missile was reportedly quite effective, it was discontinued in favor of other weapons.

Specifications

Length : 9 ft 3.5 in (2.83 m)
Finspan : 1 ft 10 in (0.56 m)
Diameter : 5 in (12.7 cm)
Weight : 155 lb (70 kg)
Propulsion : Thiokol MK 17 MOD 3 solid-fuel rocket

External links
 

AGM-087
Military equipment introduced in the 1960s
Polymethylhydrosiloxane. Polymethylhydrosiloxane (PMHS) is a polymer with the general structure . It is used in organic chemistry as a mild and stable reducing agent easily transferring hydrides to metal centers and a number of other reducible functional groups. A variety of related materials are available under the following CAS registry numbers 9004-73-3, 16066-09-4, 63148-57-2, 178873-19-3. These include the tetramer (), copolymers of dimethylsiloxane and methylhydrosiloxane, and trimethylsilyl terminated materials.

This material is prepared by the hydrolysis of monomethyldichlorosilane CAS#: 75-54-7:

The related polymer polydimethylsiloxane (PDMS) is made similarly, but lacking  bonds, it exhibits no reducing properties. Dimethyldichlorosilane CAS#: 75-78-5 is then used instead of monomethyldichlorosilane CAS#: 75-54-7.

Illustrative of its use, PMHS is used for in situ conversion of tributyltin oxide to tributyltin hydride:

References

Further reading
Larson, G. L.; Fry, J. L., "Ionic and organometallic-catalyzed organosilane reductions", Organic Reactions 2008, 71, 1-737. 

Silicones
Reagents for organic chemistry
Siloxanes
Reducing agents
AGM-123 Skipper II. AGM-123 Skipper II is a short-range laser-guided missile developed by the United States Navy. The Skipper was intended as an anti-ship weapon, capable of disabling the largest vessels with a 1,000-lb (450-kg) impact-fuzed warhead.

Design 
The AGM-123 is composed out of a  Mark 83 low-drag general purpose bomb fitted with a Paveway guidance kit and one Aerojet Mk 78 solid-propellant rocket that fires upon launch. The rocket allows the AGM-123 to be dropped farther away from the target than could free-fall bombs, which helps protect the delivery aircraft from surface-to-air-missiles and anti-aircraft artillery near the target.

The AGM-123 was developed at the China Lake Naval Weapons Center and was carried by the A-6E Intruder, A-7 Corsair II, and F/A-18.

Operational history
Four Skipper missiles launched by A-6E Intruders contributed to sinking the Iranian frigate Sahand during Operation Praying Mantis on April 18, 1988.

Skipper missiles were also fired in Operation Desert Storm against Iraqi surface vessels by A-6s and U.S. Marine aircraft.

Gallery

See also
Armement Air-Sol Modulaire

References

External links

Designation systems - Emerson Electric AGM-123 Skipper II
Federation of American Scientists - AGM-123 Skipper II

Cold War anti-ship missiles of the United States
Cold War air-to-surface missiles of the United States
Military equipment introduced in the 1980s
Silex. Silex is any of various forms of ground stone. In modern contexts the word refers to a finely ground, nearly pure form of silica or silicate.

In the late 16th century, it meant powdered or ground up "flints" (i.e. stones, generally meaning the class of "hard rocks")  

It was later used  in 1787 when describing  experiments in a published paper by Antoine Lavoisier where such earths are mentioned as the source of his isolation of the element silicon.  Silex is now most commonly used to describe finely ground silicates used as pigments in paint.

Archaic and foreign uses
 The word silex was previously used to refer to flint and chert and sometimes other hard rocks.
 In Latin silex originally referred to any hard rock, although now it often refers specifically to flint.
 In many Romance languages, silex or a similar word is used to refer to flint. Although the modern English word silex has the same etymology, its current meaning has changed. These are false friends.
 FK Sileks is a football club based in Kratovo, North Macedonia whose name literally means 'flint'.

References

Silicon
Pavements
Atomic physics
O-ring chain. The o-ring chain is a specialized type of roller chain used in the transmission of mechanical power from one sprocket to another.

Construction  

The o-ring chain is named for the rubber o-rings built into the space between the outside link plate and the inside roller link plates. Chain manufacturers began to include this feature in 1971 after the application was invented by Joseph Montano while working for Whitney Chain of Hartford, Connecticut.  O-rings were included as a way to improve lubrication to the links of power transmission chains, a service that is vitally important to extending their working life. These rubber fixtures form a barrier that holds factory applied lubricating grease inside the pin and bushing wear areas. Further, the rubber o-rings prevent dirt and other contaminants from entering the chain linkages, where such particles would otherwise cause significant wear.

Applications 

O-ring chains are most notably used in motorcycles, one of the most demanding applications for a metal chain. High rpm and heavy loads require bulky chains, but such engineering increases the effect of friction compared to lighter chains. So lubrication plays a vital role here, but the high rpm also makes it very difficult to keep lubrication inside and on the chain. Additionally, motorcycle chains are exposed to a large volume of contaminants and particles and must be protected. O-rings, as described above, fit this application perfectly.

See also 
X-ring chain
Roller chain
Motorcycle transmission

External links
 The Complete Guide to Chain
 Automatic chain oiler review

Chains
Motorcycle transmissions
Mechanical power transmission
Mechanical power control
Abenakiite-(Ce). Abenakiite-(Ce) is a mineral of sodium, cerium, neodymium, lanthanum, praseodymium, thorium, samarium, oxygen, sulfur, carbon, phosphorus, and silicon with a chemical formula Na26Ce6(SiO3)6(PO4)6(CO3)6(S4+O2)O. The silicate groups may be given as the cyclic Si6O18 grouping. The mineral is named after the Abenaki, an Algonquian Indian tribe of New England.  Its Mohs scale rating is 4 to 5.

Occurrence and association
Abenakiite-(Ce) was discovered in a sodalite syenite xenolith at Mont Saint-Hilaire, Québec, Canada, together with aegirine, eudialyte, manganoneptunite, polylithionite, serandite, and steenstrupine-(Ce).

Notes on chemistry and relation to other species
Combination of elements in abenakiite-(Ce) is unique. Somewhat chemically similar mineral is steenstrupine-(Ce). The hyper-sodium abenakiite-(Ce) is also unique in supposed presence of sulfur dioxide ligand. With a single grain (originally) found, abenakiite-(Ce) is extremely rare.

Crystal structure
In the crystal structure, described as a hexagonal net, of abenakiite-(Ce) there are:
 chains of NaO7 polyhedra, connected with PO4 groups
 columns with six-membered rings of NaO7, and NaO7-REEO6, and SiO4 polyhedra (REE – rare earth elements)
 CO3 groups, NaO6 octahedra, and disordered SO2 ligands within the columns

See also
 List of minerals

References

External links

Mindat.org
Webmineral.org

Sodium minerals
Cerium minerals
Silicate minerals
Phosphate minerals
Carbonate minerals
Trigonal minerals
Minerals in space group 148
Minerals described in 1991
Abernathyite. Abernathyite is a mineral with formula K(UO2)(AsO4)·3H2O. The mineral is named after Jesse Evrett Abernathy (1913–1963) who first noted it in 1953 in the U.S. State of Utah. It was described as a new mineral species in 1956. Abernathyite is yellow and occurs as small crystals.

Description
Abernathyite is a transparent, yellow mineral that occurs as tabular crystals up to . The mineral has a single perfect cleavage on {001}. Abernathyite fluoresces yellow-green in longwave and shortwave ultraviolet. Because of its uranium content, the mineral is radioactive.

Occurrence and formation
Abernathyite forms as a coating on fractures of asphaltic sandstone containing uranium deposits. The mineral occurs in association with heinrichite, scorodite, and zeunerite. Abernathyite is known from France, Germany, Poland, South Africa, and the United States.

Structure and formula
When first described in 1956, the formula was identified as K(UO2)(AsO4)·4H2O. However, only about 25 milligrams of the mineral was available for analysis, so a number of precautions were taken by running duplicate analyses and using artificial mixtures. In 1964, further study of the mineral identified inconsistencies between electron-density subtraction maps and the chemical evidence that abernathyite contains potassium. This led the authors to revise the formula as K(UO2)(AsO4)·3H2O.

Abernathyite crystallizes in the tetragonal crystal system.

History
Jess Abernathy was the operator of the Fuemrol mine in Emery County, Utah. In the summer of 1953, he noted yellow crystals coating sandstone at the mine which he thought might be mineralogically significant. The specimens were sent to Grand Junction, Colorado, for study by United States Atomic Energy Commission (AEC) mineralogist E. B. Gross. He could not match the mineral's optical properties with any known species, so he sent the specimens to Washington D.C. where adequate facilities were available for further investigation. Mineralogists A. D. Weeks and M. E. Thompson of the United States Geological Survey studied the mineral on behalf of the AEC's Raw Materials Division.

Abernathyite was described in the journal American Mineralogist in 1956. The mineral was named abernathyite in honor of discoverer Jess Abernathy. Type specimens are held in the National Museum of Natural History in Washington, D.C.

See also
 List of minerals

References

Bibliography

External links

Image of abernathyite from mindat.org

Uranium(VI) minerals
Potassium minerals
Arsenate minerals
Tetragonal minerals
Minerals in space group 130
Minerals described in 1956
Abhurite. Abhurite is a mineral of tin, oxygen, hydrogen, and chlorine with the formula Sn21O6(OH)14Cl16 or Sn3O(OH)2Cl2. It is named after its type locality, a shipwreck with tin ingots at Sharm Abhur, a cove near Jeddah in the Red Sea. Abhurite forms alongside other tin minerals like romarchite and cassiterite.
Abhurite can vary in color, from pale green/yellow to darker brown/green

Locality and formation 
Abhurite is attributed for forming on tin materials when in contact with sea water. The mineral was described in 1977 from a shipwreck near Hidra Island, Norway, where it occurred on pewter plates. However, that report was not recognized by the International Mineralogical Association. Along with Sharm Abhur and the shipwreck near Hidra Island, abhurite was found on tin ingots in the Uluburun shipwreck. On the ingots, it was found with other tin minerals like cassiterite and romarchite, and calcium carbonate minerals like calcite and aragonite.

See also
 List of minerals

References

Tin minerals
Chloride minerals
Trigonal minerals
Minerals in space group 155
Abswurmbachite. Abswurmbachite is a copper manganese silicate mineral ((Cu,Mn2+)Mn3+6O8SiO4). It was first described in 1991 and named after Irmgard Abs-Wurmbach (born 1938), a German mineralogist.  It crystallizes in the tetragonal system. Its Mohs scale rating is 6.5 and a specific gravity of 4.96.  It has a metallic luster and its color is jet black, with light brown streaks.

See also
List of minerals
List of minerals named after people

References

Mindat.org – Abswurmbachite
Webmineral.com – Abswurmbachite
Handbook of Mineralogy – Abswurmbachite 

Nesosilicates
Tetragonal minerals
Minerals in space group 142
Acuminite. Acuminite is a rare halide mineral with chemical formula: SrAlF4(OH)·(H2O).  Its name comes from the Latin word acumen, meaning "spear point".  Its Mohs scale rating is 3.5.

Acumenite has only been described from its type locality of the cryolite deposit in Ivigtut, Greenland.

See also
 List of minerals

References

Strontium minerals
Aluminium minerals
Fluorine minerals
Monoclinic minerals
Minerals in space group 15
Minerals described in 1987
Helmholtz theorem (classical mechanics). The Helmholtz theorem of classical mechanics reads as follows:

Let  be the Hamiltonian of a one-dimensional system, where  is the kinetic energy and   is a "U-shaped" potential energy profile which depends on a parameter .
Let  denote the time average. Let 

Then

Remarks 
The thesis of this theorem of classical mechanics reads exactly as the heat theorem of thermodynamics. This fact shows that thermodynamic-like relations exist between certain mechanical quantities. This in turn allows to define the "thermodynamic state" of a one-dimensional mechanical system. In particular the temperature  is given by time average of the kinetic energy, and the entropy  by the logarithm of the action (i.e., ). 
The importance of this theorem has been recognized by Ludwig Boltzmann who saw how to apply it to macroscopic systems (i.e. multidimensional systems), in order to provide a mechanical foundation of equilibrium thermodynamics. This research activity was strictly related to his formulation of the ergodic hypothesis.
A multidimensional version of the Helmholtz theorem, based on the ergodic theorem of George David Birkhoff is known as the generalized Helmholtz theorem.

Generalized version 
The generalized Helmholtz theorem is the multi-dimensional generalization of the Helmholtz theorem, and reads as follows.

Let

be the canonical coordinates of a s-dimensional Hamiltonian system, and let

be the Hamiltonian function, where

,

is the kinetic energy and

is the potential energy which depends on a parameter .
Let the hyper-surfaces of constant energy in the 2s-dimensional phase space of the system be metrically indecomposable and let  denote time average. Define the quantities , , , , as follows:

,

,

,

Then:

References 
Helmholtz, H., von (1884a). Principien der Statik monocyklischer Systeme. Borchardt-Crelle’s Journal für die reine und angewandte Mathematik, 97, 111–140 (also in Wiedemann G. (Ed.) (1895) Wissenschafltliche Abhandlungen. Vol. 3 (pp. 142–162, 179–202). Leipzig: Johann Ambrosious Barth).
Helmholtz, H., von (1884b). Studien zur Statik monocyklischer Systeme. Sitzungsberichte der Kö niglich Preussischen Akademie der Wissenschaften zu Berlin, I, 159–177 (also in Wiedemann G. (Ed.) (1895) Wissenschafltliche Abhandlungen. Vol. 3 (pp. 163–178). Leipzig: Johann Ambrosious Barth).
Boltzmann, L. (1884). Über die Eigenschaften monocyklischer und anderer damit verwandter Systeme.Crelles Journal, 98: 68–94 (also in Boltzmann, L. (1909). Wissenschaftliche Abhandlungen (Vol. 3, pp. 122–152), F. Hasenöhrl (Ed.). Leipzig. Reissued New York: Chelsea, 1969).
Gallavotti, G. (1999). Statistical mechanics: A short treatise. Berlin: Springer.
Campisi, M. (2005) On the mechanical foundations of thermodynamics: The generalized Helmholtz theorem Studies in History and Philosophy of Modern Physics 36: 275–290

Classical mechanics
Statistical mechanics theorems
Hermann von Helmholtz
Adamsite-(Y). Adamsite-(Y) (previously IMA 1999-020), chemical formula NaY(CO3)2·6H2O is a mineral of sodium, yttrium, carbon, oxygen, and hydrogen. It is named after Frank Dawson Adams (1859–1942), professor of geology, McGill University. Its Mohs scale rating is 3.

See also
 List of minerals
 List of minerals named after people

References

External links

Mindat.org - Adamsite-(Y)
Webmineral.com - Adamsite-(Y)
Handbook of Minerals - Adamsite-(Y) 

Sodium minerals
Yttrium minerals
Carbonate minerals
Triclinic minerals
Minerals in space group 2