omniomni/omni-engineering huggingface dataset:
Ledeburite. In iron and steel metallurgy, ledeburite is a mixture of 4.3% carbon in iron and is a eutectic mixture of austenite and cementite. Ledeburite is not a type of steel as the carbon level is too high although it may occur as a separate constituent in some high carbon steels. It is mostly found with cementite or pearlite in a range of cast irons.

It is named after the metallurgist Karl Heinrich Adolf Ledebur (1837–1906). He was the first professor of metallurgy at the Bergakademie Freiberg and discovered ledeburite in 1882.

Ledeburite arises when the carbon content is between 2.06% and 6.67%. The eutectic mixture of austenite and cementite is 4.3% carbon, Fe3C:2Fe, with a melting point of 1147 °C.

Ledeburite-II (at ambient temperature) is composed of cementite-I with recrystallized secondary cementite (which separates from austenite as the metal cools) and (with slow cooling) of pearlite. The pearlite results from the eutectoidal decay of the austenite that comes from the ledeburite-I at 723 °C. During more rapid cooling, bainite can develop instead of pearlite, and with very rapid cooling martensite can develop.

Origins and discovery

The story of ledeburite begins in the late 19th century when Adolf Ledebur, a pioneering German metallurgist, embarked on a journey to unravel the complexities of steel microstructures. In 1882, Ledebur identified a distinct microconstituent in high-carbon steels, characterized by its unique lamellar structure. This discovery marked the birth of ledeburite, named in honor of the scientist whose keen observations laid the foundation for understanding the intricate world within steel.

Significance in metallurgical studies

Beyond its immediate industrial applications, ledeburite holds a central position in metallurgical studies. The exploration of this unique microconstituent contributes to a deeper understanding of phase transformations, solidification processes, and the principles governing alloy behavior. Researchers and metallurgists leverage ledeburite as a model system to investigate the fundamental aspects of phase diagrams, eutectic reactions, and the kinetics of microstructural evolution during cooling and solidification.

Metallurgical studies involving ledeburite extend to the development of advanced materials with tailored properties. By comprehending the nuances of ledeburite formation and its impact on steel performance, scientists can design alloys with improved strength, hardness, and corrosion resistance. This knowledge is invaluable in pushing the boundaries of material science and engineering, paving the way for innovations in diverse fields.

External links
Names and Steel
Karl Heinrich Adolf Ledebur (in German)
Rostfreier Edelstahl (in German)

Metallurgy
Ferrous alloys
Bridge of Awe. The Bridge of Awe () was a triple-spanned arch bridge near Taynuilt in Argyll, Scotland.

History

In 1753 the Bonawe Iron Furnace was constructed on the north side of Taynuilt. The furnace was of such strategic importance that in 1756 a military road was built to reach it, crossing the Pass of Brander and the Bridge of Awe. Despite flooding during construction, which swept away the partially built bridge, it was completed in 1779. It was twenty years before the road was extended westward to Connel, and later still to Oban.

The original bridge featured in the 1959 film 'The Bridal Path' starring George Cole and Gordon Jackson.

A reinforced concrete bridge was built in 1938 as a replacement for the old bridge. This is still in use today, carrying the A85 road from Oban to Dalmally over the River Awe.

The original bridge was destroyed in January 1992 following heavy floods. High winds had damaged the roof of the Inverawe Power Station, resulting in its temporary closure. Minimal water was drained from Loch Awe until the gates were opened to their maximum to relieve the level of Loch Awe and the Awe Barrage from overflowing. Two of the three arches of the old bridge were washed away, with one arch on the Taynuilt bank remaining, in part due to the deflection of the main flow by the small island upstream.

The course of the river has changed greatly since the 1992 floods. The island upstream now joins to the land on the Taynuilt bank in summer months when the river is low.

Footnotes

Road bridges in Scotland
Bridges completed in 1756
Bridges completed in 1938
Category B listed buildings in Argyll and Bute
Listed bridges in Scotland
Bridges in Argyll and Bute
R++. R++ is a rule-based programming language based on C++,  described as follows:
The R++ extension permits rules to be defined as members of C++ classes. The programming system of the invention takes the classes with rules defined using R++ and generates C++ code from them in which the machinery required for the rules is implemented completely as C++ data members and functions of the classes involved in the rules.

R++ was developed by Bell Labs in the 1990s, but due to the Bell System divestiture that split the legal rights to the work developed at the Laboratories between AT&T and Lucent, did not see immediate commercial development while the two companies disputed ownership.

References 

C++ programming language family
Alberto Romão Dias. Alberto Romão Dias (1941 – 15 July 2007) was a full professor of the Chemical and Biological Engineering Department at the Instituto Superior Técnico (IST) of the Technical University of Lisbon in Portugal.

Education 
His alma mater includes graduating from industrial-chemical engineering at the Instituto Superior Técnico in 1964, a Ph.D. in chemistry from Oxford University in 1970, and Aggregation at the Instituto Superior Técnico in 1979.

Research works 
His research interests were in the area of inorganic chemistry, particularly chemistry of coordination compounds and the organometallic chemistry of transition metals. The latter work has been on mono and polynuclear complex containing the fragment M(η5-C5H5)2.

Other topics in which he was interested include the synthesis of complexes with ligands containing phosphorus, reactions of metal vapours with different substrates aiming at the synthesis of new compounds, and the preparation of species with catalytic polymerization of olefins using transition metal complexes.

Recent research in this group includes the synthesis of new organometallic compounds (some of them with nonlinear optical properties), their characterisation (including the X-ray determination of the molecular structure), the study of their reactivity and of their redox behaviour, the determination of the metal-ligand bond energies from data obtained by calorimetry and the study of chemical bond using molecular orbital theory.

Dias published the book Ligação Química (English: Chemical Bond) in October 2006. This text is used mainly as a study guide for "Chemistry I" students at the Instituto Superior Técnico.

Alberto Romão Dias died on 15 July 2007.

External links
VIII Governo Constitucional
Alberto Romão Dias at IST

1941 births
2007 deaths
Alumni of the University of Oxford
Instituto Superior Técnico alumni
20th-century Portuguese people
Portuguese chemists
Portuguese chemical engineers
Bradfield School. Bradfield School is a secondary school with academy status situated on the edge of the village of Worrall, in the civil parish of Bradfield, in Sheffield, South Yorkshire, England. The school is a specialist Engineering College formerly catering for pupils between the ages of 11 and 18. However, as of September 2019, the school's sixth form has closed down and the school now only caters to between the ages of 11 and 16.

Curriculum 

At Key Stage 4 Bradfield provides students with a broad and balanced curriculum in line with the National Curriculum. All students take Citizenship (Half GCSE), English Language (One GCSE), English Literature (One GCSE), ICT (One GCSE), Mathematics (One GCSE), Physical Education (One GCSE), and Religious Education (Half GCSE) and Science Double Award (Two GCSEs).

Achievements

2006 
The Bradfield Panthers, an F1 In Schools team won the British national finals.

References 

Secondary schools in Sheffield
Academies in Sheffield
Educational institutions established in 1957
1957 establishments in England
Specialist engineering colleges in England
Nurman Avia. Nurman Avia was an airline based in Jakarta, Indonesia. It operated passenger and cargo charters out of Soekarno-Hatta International Airport, Jakarta.

History 
The airline was established in 1997 as a sister company to HeavyLift Indonesia, operating charter flights on behalf of Bouraq Indonesia Airlines and Sempati Air. In 2007, the airline was shut down.

Fleet 
As of March 2007 the Nurman Avia fleet included the following aircraft:

 Fokker F28 Mk4000

References 

Defunct airlines of Indonesia
Airlines established in 1997
Airlines disestablished in 2007
1997 establishments in Indonesia
2007 disestablishments in Indonesia
Specific surface area. Specific surface area (SSA) is a property of solids defined as the total surface area (SA) of a material per unit mass, (with units of m2/kg or m2/g). Alternatively, it may be defined as SA per solid or bulk volume (units of m2/m3 or m−1).

It is a physical value that can be used to determine the type and properties of a material (e.g. soil or snow). It has a particular importance for adsorption, heterogeneous catalysis, and reactions on surfaces.

Measurement

Values obtained for specific surface area depend on the method of measurement. In adsorption based methods, the size of the adsorbate molecule (the probe molecule), the exposed crystallographic planes at the surface and measurement temperature all affect the obtained specific surface area. For this reason, in addition to the most commonly used Brunauer–Emmett–Teller (N2-BET) adsorption method, several techniques have been developed to measure the specific surface area of particulate materials at ambient temperatures and at controllable scales, including methylene blue (MB) staining, ethylene glycol monoethyl ether (EGME) adsorption, electrokinetic analysis of complex-ion adsorption and a Protein Retention (PR) method. A number of international standards exist for the measurement of specific surface area, including ISO standard 9277.

Calculation
The SSA can be simply calculated from a particle size distribution, making some assumption about the particle shape.  This method, however, fails to account for surface associated with the surface texture of the particles.

Adsorption
The SSA can be measured by adsorption using the BET isotherm. This has the advantage of measuring the surface of fine structures and deep texture on the particles. However, the results can differ markedly depending on the substance adsorbed. The BET theory has inherent limitations but has the advantage to be simple and to yield adequate relative answers when the solids are chemically similar. In relatively rare cases, more complicated models based on thermodynamic approaches, or even quantum chemistry, may be applied to improve the consistency of the results, but at the cost of much more complex calculations requiring advanced knowledge and a good understanding from the operator.

Gas permeability

This depends upon a relationship between the specific surface area and the resistance to gas-flow of a porous bed of powder.  The method is simple and quick, and yields a result that often correlates well with the chemical reactivity of a powder.  However, it fails to measure much of the deep surface texture.

See also

 Surface-area-to-volume ratio

References

Porous media
Surface science
A
Sussman anomaly. The Sussman anomaly is a problem in artificial intelligence, first described by Gerald Sussman, that illustrates a weakness of noninterleaved planning algorithms, which were prominent in the early 1970s. Most modern planning systems are not restricted to noninterleaved planning and thus can handle this anomaly. While the significance/value of the problem is now a historical one, it is still useful for explaining why planning is non-trivial. In the problem, three blocks (labeled A, B, and C) rest on a table.  The agent must stack the blocks such that A is atop B, which in turn is atop C. However, it may only move one block at a time.  The problem starts with B on the table, C atop A, and A on the table:

However, noninterleaved planners typically separate the goal (stack A atop B atop C) into subgoals, such as:
 get A atop B
 get B atop C

Suppose the planner starts by pursuing Goal 1. The straightforward solution is to move C out of the way, then move A atop B. But while this sequence accomplishes Goal 1, the agent cannot now pursue Goal 2 without undoing Goal 1, since both A and B must be moved atop C:

If instead the planner starts with Goal 2, the most efficient solution is to move B. But again, the planner cannot pursue Goal 1 without undoing Goal 2:

The problem was first identified by Sussman as a part of his PhD research.  Sussman (and his supervisor, Marvin Minsky) believed that intelligence requires a list of exceptions or tricks, and developed a modular planning system for "debugging" plans.

See also
STRIPS
Automated planning
Greedy algorithm

Sources

G.J. Sussman (1975) A Computer Model of Skill Acquisition Elsevier Science Inc. New York, NY, USA.  Book version of his PhD thesis.

Automated planning and scheduling
1975 introductions
Cummins M-series engine. The Cummins M-series engine is a straight-six diesel engine designed and produced by Cummins. It displaces . Introduced as the M11 in 1994, it was built on the previous L10 engine (same  cylinder bore, but a longer  piston stroke compared to the L10's  stroke).

Later M11's received the electronic CELECT and CELECT Plus fuel systems consisting of a gear pump and solenoid controlled injectors. The M11 CELECT Plus became the ISM when Cummins applied its Interact System (hence the "IS" in ISM) to the M11 CELECT Plus in 1998 to further improve the engine. The ISM is available in four configurations, with slightly-different emphasis on maximum power ( vs. ) and peak torque.

Applications
 Large transit buses (40 feet and up).
 Coaches
 Large fire trucks
 Heavy-duty trucks
 Off-Highway (QSM11)

Popular power ratings
Urban bus
 @ 1200 rpm,  (209 kW) electronically governed at 2,100 rpm
 @ 1200 rpm,  (246 kW) electronically governed at 2,100 rpm
RV, Truck, Motorcoach
 @ 1200 rpm,  (209 kW) electronically governed at 2,100 rpm
 @ 1200 rpm,  (246 kW) electronically governed at 2,100 rpm
 @ 1200 rpm,  (209 kW) electronically governed at 2,100 rpm
 @ 1200 rpm,  (246 kW) electronically governed at 2,100 rpm
 @ 1200 rpm,  (209 kW) electronically governed at 2,100 rpm
 @ 1200 rpm,  (246 kW) electronically governed at 2,100 rpm
 @ 1200 rpm,  (246 kW) electronically governed at 2,100 rpm
 @ 1200 rpm,  (246 kW) electronically governed at 2,100 rpm
 @ 1200 rpm,  (246 kW) electronically governed at 2,100 rpm
 @ 1200 rpm,  (246 kW) electronically governed at 2,100 rpm
 @ 1200 rpm,  (246 kW) electronically governed at 2,100 rpm

References

External links
Cummins ISM

Cummins diesel engines
Diesel engines by model
Straight-six engines
Moladi. Moladi is a South African company specializing in a reusable plastic formwork for use in construction of affordable housing projects worldwide. The process involves creating a mold of the form of the complete structure. This wall mold is then filled with an aerated form of Mortar. The construction process is faster than traditional methods of construction.

The technology has won the Design for Development award of the South African Bureau of Standards Design Institute in 1997, with the institute praising Moladi as:
''...an interlocking and modular formwork or shutter system for molding complex monolithic reinforced structures. The modular plastic panels are lightweight and extremely robust. The building method is especially suited for affordable low-cost, mass housing schemes.
In addition to being a part of the drive by the South African government to replace shantytowns with proper houses, Moladi also exports to 26 countries like Panama Democratic Republic of the Congo Tanzania and others.
Moladi solves key low-cost challenges - The company production plant is based in Port Elizabeth

References 
 Future of Construction - World Economic Forum - World Bank

External links 
 

Construction and civil engineering companies of South Africa
Home builders
Construction
Foy's Lake. Foy's Lake is a man-made lake in Chittagong, Bangladesh. It was created in 1924 by constructing a dam across the stream that came down from the hills in the northern part of Chittagong. The purpose of creating an artificial lake was to provide water to the residents of the railway colony. It was named after Mr. Foy, a Railway engineer, believed to materialize said project. Pahartali was essentially a railway town containing a workshop, yard, and shed. Presently, a carriage workshop, diesel workshop, loco shed, laboratory, stores, electric workshop, and school (established in 1924) are located here. A good number of railway employees reside in the nearby colony.

The area belongs to Railway. However, an amusement park, managed by the Concord Group, is located here.

Gallery

External links

Faiz Lake. In: GeoNames.org

References

Reservoirs in Bangladesh
Tourist attractions in Chittagong Division
Geography of Chittagong
Dioxygenyl. The dioxygenyl ion, , is a rarely-encountered oxycation in which both oxygen atoms have a formal oxidation state of .  It is formally derived from oxygen by the removal of an electron:

O2 →  + e−

The energy change for this process is called the ionization energy of the oxygen molecule.  Relative to most molecules, this ionization energy is very high at 1175 kJ/mol. As a result, the scope of the chemistry of  is quite limited, acting mainly as a 1-electron oxidiser.

Structure and molecular properties
 has a bond order of 2.5, and a bond length of 112.3 pm in solid O2[AsF6]. It is isoelectronic with nitric oxide and is paramagnetic. The bond energy is 625.1 kJ mol−1 and the stretching frequency is 1858 cm−1, both of which are high relative to most of the molecules.

Synthesis

Neil Bartlett demonstrated that dioxygenyl hexafluoroplatinate (O2PtF6), containing the dioxygenyl cation, can be prepared at room temperature by direct reaction of oxygen gas (O2) with platinum hexafluoride (PtF6):

O2 + PtF6 → 

The compound can also be prepared from a mixture of fluorine and oxygen gases in the presence of a platinum sponge at 450 °C, and from oxygen difluoride () above 400 °C:

6  + 2 Pt → 2  + 

At lower temperatures (around 350 °C), platinum tetrafluoride is produced instead of dioxygenyl hexafluoroplatinate.  Dioxygenyl hexafluoroplatinate played a pivotal role in the discovery of noble gas compounds.  The observation that PtF6 is a powerful enough oxidising agent to oxidise O2 (which has a first ionization potential of 12.2 eV) led Bartlett to reason that it should also be able to oxidise xenon (first ionization potential 12.13 eV). His subsequent investigation yielded the first compound of a noble gas, xenon hexafluoroplatinate.

 is also found in similar compounds of the form O2MF6, where M is arsenic (As), antimony (Sb), gold (Au), niobium (Nb), ruthenium (Ru), rhenium (Re), rhodium (Rh), vanadium (V), or phosphorus (P). Other forms are also attested, including O2GeF5 and (O2)2SnF6.

The tetrafluoroborate and hexafluorophosphate salts may be prepared by the reaction of dioxygen difluoride with boron trifluoride or phosphorus pentafluoride at −126 °C:

2 O2F2 + 2 BF3 → 2 O2BF4 + F2
2 O2F2 + 2 PF5 → 2 O2PF6 + F2

These compounds rapidly decompose at room temperature:
2 O2BF4 → 2 O2 + F2 + 2 BF3
2 O2PF6 → 2 O2 + F2 + 2 PF5

Some compounds including O2Sn2F9, O2Sn2F9·0.9HF, O2GeF5·HF, and O2[Hg(HF)]4(SbF6)9 can be made by ultraviolet irradiation of oxygen and fluorine dissolved in anhydrous hydrogen fluoride with a metal oxide.

All attempts to prepare  with chloro anions like  met with failure.

Reactions

The reaction of O2BF4 with xenon at  produces a white solid believed to be F–Xe–BF2, containing an unusual xenon-boron bond:

2 O2BF4 + 2 Xe → 2 O2 + F2 + 2 FXeBF2

The dioxygenyl salts O2BF4 and O2AsF6 react with carbon monoxide to give oxalyl fluoride, C2O2F2, in high yield.

References

External links

Oxycations
Oxygen
Total dynamic head. In fluid dynamics, total dynamic head (TDH) is the work to be done by a pump, per unit weight, per unit volume of fluid. TDH is the total amount of system pressure, measured in feet, where water can flow through a system before gravity takes over, and is essential for pump specification.

 

 TDH = Static Lift + Pressure Head + Velocity Head + Friction Loss 

where:
 Static lift is the difference in elevation between the suction point and the discharge point.
 Pressure head is the difference in pressure between the suction point and the discharge point, expressed as an equivalent height of fluid.
 Velocity head represents the kinetic energy of the fluid due to its bulk motion.
 Friction loss (or head loss) represents energy lost to friction as fluid flows through the pipe.
This equation can be derived from Bernoulli's Equation.

For incompressible liquids such as water, Static lift + Pressure head together equal the difference in fluid surface elevation between the suction basin and the discharge basin.

See also
 Hydraulic head
 Fluid dynamics

External links
 http://www.wolframalpha.com/input/?i=total+dynamic+head -wolframalpha.com
 https://www.pumpproducts.com/blog/how-to-calculate-total-dynamic-head-for-a-pump

Fluid mechanics
Laboratory for Electromagnetic and Electronic Systems. The Laboratory for Electromagnetic and Electronic Systems (LEES) at the Massachusetts Institute of Technology (MIT) provides the theoretical basis, and component, circuit and system technologies required to develop advanced electrical energy applications. LEES research areas include electronic circuits, components and systems, power electronics and control, micro and macro electromechanics, electromagnetics, continuum mechanics (the interaction of fields with fluids and other deformable media), high voltage engineering and dielectric physics, manufacturing and process control, and energy economics.

In 2009 the LEES ceased to exist as a separate lab and was administratively merged into the Research Laboratory of Electronics to form its seventh research theme.

References

External links
The LEES official website 
The MIT official website

Massachusetts Institute of Technology