omniomni/omni-engineering huggingface dataset:
Tactical bombing. Tactical bombing is aerial bombing aimed at targets of immediate military value, such as combatants, military installations, or military equipment. This is in contrast to strategic bombing, or attacking enemy cities and factories to cripple future military production and enemy civilians' will to support the war effort, to debilitate the enemy's long-term capacity to wage war. The term "tactical bomber" only refers to a bomber aircraft designed specifically for the primary role of tactical bombing, even though many other types of aircraft ranging from strategic bombers to fighters, interceptors, and helicopters have been used in tactical bombing operations.

Tactical bombing is employed for two primary assignments.  Aircraft providing close air support attack targets in nearby proximity to friendly ground forces, acting in direct support of the ground operations (as a "flying artillery"). Air interdiction, by contrast, attacks tactical targets that are distant from or otherwise not in contact with friendly units.

History
Tactical bombing was the first type of aerial bombing mission. It began in the Italo-Turkish War when pilots dropped small bombs over the side of their open cockpits onto enemy troops below. One of the earliest examples of tactical bombing was at the Battle of Neuve Chapelle in 1915 when the Royal Flying Corps dropped bombs on German rail communications. By the time of World War II a number of specialized aircraft were developed to fulfill this role, including various fighter-bombers.  During the Korean War tactical bombing missions were sometimes carried out by older piston-powered fighters such as the Vought F4U Corsair. In the Vietnam War, missions were frequently directed by Forward air controllers (FACs) flying small propeller-driven planes. The FAC would mark targets with smoke, often in coordination with infantry on the ground.  Bombers orbiting overhead would then fly in to hit the target.  

In the modern era, precision-guided munitions ("smart bombs") can be directed with extreme accuracy. Dedicated tactical bomber aircraft types have largely been supplanted by fighter-bombers and strike aircraft.

See also
 List of established military terms
 Strategic bombing
 Tactical Air Command (United States)
 Carpet bombing
 Close air support
 Forward air control
 Attack aircraft
 Suppression of Enemy Air Defenses
 Gunship
 Air interdiction
 Tank plinking

References

Military aviation
Aerial bombing
Aerial maneuvers
Military terminology
Stephen C. Johnson. Stephen Curtis Johnson (born 1944) is a computer scientist who worked at Bell Labs and AT&T for nearly 20 years. He is best known for Yacc, Lint, spell, and the Portable C Compiler, which contributed to the spread of Unix and C. He has also contributed to fields as diverse as computer music, psychometrics and VLSI design.

Life and education
Johnson's passion for computing started at age five, when his grandfather took him along to his work at the Bureau of Standards. The computer he saw ("the size of a small house") made a strong impression on him, and he decided he "wanted to work with computers, and never looked back after".

There were no computer science classes in college, so he studied mathematics, in which he eventually earned a PhD.

Career

Bell Labs and AT&T
Johnson joined Bell Labs and AT&T in the 1960s and worked on Unix tools for nearly 20 years, alongside computer scientists like Jeffrey Ullman, Dennis Ritchie and Alfred Aho. He was best known for writing Yacc, Lint, and the Portable C Compiler.

In the mid-1970s, Johnson and Bell colleague Dennis Ritchie co-authored the first AT&T Unix port. They also "demonstrated that Unix was portable", which Ritchie considers the spark that led to Unix becoming widespread. In the mid-1980s, he served as the head of the UNIX Languages Department (UNIX System V).

Johnson developed Yacc in the early '70s because he wanted to insert an exclusive or operator into Ritchie's B language compiler. Bell Labs colleague Alfred Aho suggested he look at Donald Knuth's work on LR parsing, which served as the basis for Yacc. In a 2008 interview, Johnson reflected that "the contribution Yacc made to the spread of Unix and C is what I'm proudest of". Lint was developed in 1978 while Johnson was debugging the Yacc grammar he was writing for C and struggling with portability issues stemming from porting Unix to a 32-bit machine.

Silicon Valley
In 1986, Johnson moved to Silicon Valley, where he joined several startups, where he worked mostly on compilers, but also 2D and 3D graphics, massively parallel computing and embedded systems. The startups included Dana Computer, Inc., Melismatic Software, and Transmeta, which made low-power, Intel-compatible microprocessors.

Johnson served on the USENIX board for ten years, including four years as president in the early 1990s. He now serves as the USENIX representative to the Computing Research Association.

Later career

In 2002, he moved to Boston to work at MathWorks, where he helped maintain the front end of the MATLAB programming language, for which he also built a lint product called M-Lint. He had met MathWorks founder Cleve Moler while working at a Silicon Valley startup and developed a "long-distance consulting relationship" with him in the 1990s.

As of 2018 Johnson currently lived in Morgan Hill, California busy working on energy-efficient computers for machine learning at Wave Computing.

References 

Unix people
Scientists at Bell Labs
Living people
1944 births
Benjamin B. Hotchkiss. Benjamin Berkeley Hotchkiss (October 1, 1826 – February 14, 1885) was one of the leading American ordnance engineers of his day.

American career
Hotchkiss was born in Watertown, Connecticut, and moved to Sharon, Connecticut in childhood; his early experiments were made there in his father's hardware factory.  Starting in the 1850s, he was employed as a gunmaker in Hartford, working on Colt revolvers and Winchester rifles.

Hotchkiss patented a line of projectiles for rifled artillery that were used extensively in the American Civil War.

French career 

After the American Civil War, the U.S. government showed little interest in funding new weapons. In 1867, Hotchkiss moved to France and set up a munitions factory, first in Viviez, near Rodez, then in Saint-Denis, near Paris, named Hotchkiss et Cie. At about this time, he developed a revolving barrel machine gun (in French: "canon-revolver") known as the Hotchkiss gun; the gun was made in four sizes from 37 mm to 57 mm, the largest intended for naval use. After his death, the Hotchkiss company also developed in 1897 and later manufactured in large numbers an air-cooled, gas-actuated infantry machine gun which was widely used by several countries, particularly France and the United States during the First World War.

Personal life

On May 27, 1850, he married Maria Bissell Hotchkiss, who after his death founded The Hotchkiss School in Lakeville, Connecticut, and the Hotchkiss Library in Sharon.  Hotchkiss committed bigamy when he married a Miss Cunningham in a French civil ceremony in Paris in 1867;

References

Bibliography

External links
Hotchkiss's patent application for Improvement in Projectiles for Rifled Ordnance
Brief biography of Benjamin Hotchkiss

1826 births
1885 deaths
American engineers
19th-century American inventors
American pioneers
People of Connecticut in the American Civil War
Benjamin Hotchkiss
Military personnel from Connecticut
People from Watertown, Connecticut
People from Sharon, Connecticut
Kolbe electrolysis. 

The Kolbe electrolysis or Kolbe reaction is an organic reaction named after Hermann Kolbe. The Kolbe reaction is formally a decarboxylative dimerisation of two carboxylic acids (or carboxylate ions). The overall reaction is:

If a mixture of two different carboxylates are used, all combinations of them are generally seen as the organic product structures:

 3 R1COO− + 3 R2COO− → R1−R1 + R1−R2 + R2−R2 + 6 CO2 + 6 e−

The reaction mechanism involves a two-stage radical process: electrochemical decarboxylation gives a radical intermediate, which combine to form a covalent bond. As an example, electrolysis of acetic acid yields ethane and carbon dioxide:
CH3COOH → CH3COO− → CH3COO· → CH3· + CO2 
2CH3· → CH3CH3

Another example is the synthesis of 2,7-dimethyl-2,7-dinitrooctane from 4-methyl-4-nitrovaleric acid:

The Kolbe reaction has also been occasionally used in cross-coupling reactions.

In 2022, it was discovered that the Kolbe electrolysis is enhanced if an alternating square wave current is used instead of a direct current.

Applications
Kolbe electrolysis has a few industrial applications.  In one example, sebacic acid has been produced commercially by Kolbe electrolysis of adipic acid.

Kolbe electrolysis has been examined for converting biomass into biodiesel and for grafting of carbon electrodes.

See also
 Electrosynthesis
 Wurtz reaction

References

Further reading

External links
 

Organic redox reactions
Electrolysis
Name reactions
Riparian forest. A riparian forest or riparian woodland is a forested or wooded area of land adjacent to a body of water such as a river, stream, pond, lake, marshland, estuary, canal, sink or reservoir.

Etymology

The term riparian comes from the Latin word ripa, 'river bank'; technically it refers only to areas adjacent to flowing bodies of water such as rivers, streams, sloughs and estuaries.  However, the terms riparian forest and riparian zone have come to include areas adjacent to non-flowing bodies of water such as ponds, lakes, playas and reservoirs.

Characteristics

Riparian forests are subject to frequent inundation.

Riparian forests help control sediment, reduce the damaging effects of flooding and aid in stabilizing stream banks.

Riparian zones are transition zones between an upland terrestrial environment and an aquatic environment.  Organisms found in this zone are adapted to periodic flooding.  Many not only tolerate it, but require it in order to maintain health and complete their lifestyles.

Threats
Threats to riparian forests:

 Cleared for agricultural use because of the good soil quality
 Historically, trees used as wood fuel for steamships, steam locomotives, etc.
 Urban development (housing, roads, malls, etc.)
 Grazing 
 Mining
 Disrupted hydrology, such as dams and levees, which reduces the amount and/or frequency of flooding
 Invasive species

See also
 Bosque
 Gallery forest
 Management of Pacific Northwest riparian forests
 Riparian zone
 Tugay
 Swamp Oak Forests

References

External links
 "Assessing the Need for a Riparian Management System (RiMS)"—Iowa State University Extension Bulletin (2002)

Forests
Habitats
Riparian zone
Traction substation. A traction substation, traction current converter plant, rectifier station or traction power substation (TPSS) is an electrical substation that converts electric power from the form provided by the electrical power industry for public utility service to an appropriate voltage, current type and frequency to supply railways, trams (streetcars) or trolleybuses with traction current.

Conversions
These systems can be used to convert three-phase 50 Hz or 60 Hz alternating current (AC) for the supply of AC railway electrification systems at a lower frequency and single phase, as used by many older systems, or to rectify AC into direct current (DC) for those systems (primarily public transit systems) using DC for traction power. The three-phase voltage from the local utility is stepped down and rectified in the traction substations to provide the required DC voltage.

Equipment

Rotating
Originally, the conversion equipment usually consisted of one or more motor-generator sets containing three-phase synchronous AC motors and single-phase AC generators, mechanically coupled to a common shaft. Rotary converters were also used, especially where the desired output was DC current from an AC source.

Static
In the 1920s, DC was derived using electronic valves (mercury arc rectifiers). In modern systems, high-voltage DC (HVDC) "back-to-back" stations are used instead of mechanical equipment to convert between different frequencies and phases of AC power and solid-state thyristor rectifier systems are used for conversion from AC power to DC traction power.

Location
Traction current converter plants are either decentralized (where one plant directly supplies the overhead lines or third rail of the traction system, with no feed into a traction current distribution network) or centralized (for the supply of the traction power network, usually in addition to the direct supply of the overhead lines or third rail).

Central traction current converter plants are generally found in Germany (primarily in the cities of Neckarwestheim, Ulm, Nuremberg), Austria and Switzerland, while decentralized traction current converter plants are generally found in Norway, Sweden and the German states of Mecklenburg-Vorpommern and Brandenburg as well as parts of Great Britain. A List of railway electrification systems provides further detail.

See also
 Traction powerstation
 Trolleybus
 Railway electrification system

Electrical substations
Electric rail transport
Traction power networks
Fritz Mueller. Dr. Fritz K. Mueller (1907 – 2001 Huntsville, Alabama, USA) was a German engineer.

Mueller was hired by Kreiselgeräte Company in 1930. He developed the PIGA accelerometer. and worked on gyroscopes for Nazi Germany's Kriegsmarine. Later on, he worked on the guidance and control system for the A3 test rocket, the A5, and the A4 (V2) ballistic missile.

Under Project Paperclip, Mueller emigrated to the United States on 16 November 1945 with the Argentina group. There, he worked on developing guidance systems for the PGM-11 Redstone, PGM-19 Jupiter, MGM-31 Pershing, and the Saturn I missiles.
In 1960 Mueller left NASA for private industry.

References

1907 births
2001 deaths
Early spaceflight scientists
German aerospace engineers
German spaceflight pioneers
Operation Paperclip
Traction current pylon. A traction current pylon is a railroad pylon carrying at least one circuit for traction current. In Germany, traction current lines with two systems (4 conductor cables) typically have a single level arrangement of the conductor cables. For traction current lines with four systems (8 conductor cables), the two-level arrangement (4 conductor cables on each crossbar) is frequently used, except for traction current lines supplying high-speed railway lines are used. For these lines a three-level arrangement is used, in which the lowest cross bar has four conductor cables and each of the two highest cross bars have two conductor cables. The three-level arrangement is also used for traction current pylons with 6 electric circuits (12 conductor cables). For the supply of rapid-transit railways operated with alternating current, some overhead line pylons have cross bars for traction current lines above the contact wire. Other pylons carry electric circuits for traction current and also for three-phase alternating current.

See also 
 Gantry
 Railway traction line towers
 Utility pole
 Overhead line

Pylons
Electric power infrastructure
MIC-1. The MIC-1 is a CPU architecture invented by Andrew S. Tanenbaum to use as a simple but complete example in his teaching book Structured Computer Organization.

It consists of a very simple control unit that runs microcode from a 512-words store.

The Micro-Assembly Language (MAL) is engineered to allow simple writing of an IJVM interpreter, and the source code for such an interpreter can be found in the book.

Hardware

Data path 

The data path is the core of the MIC-1. It contains 32-bit registers, buses, an ALU and a shifter.

Buses 

There are 2 main buses of 32 lines (or 32 bits) each:

 B bus: connected to the output of the registers and to the input of the ALU.
 C bus: connected to the output of the shifter and to the input of the registers.

Registers 

Registers are selected by 2 control lines: one to enable the B bus and the other to enable the C bus.
The B bus can be enabled by just one register at a time, since the transfer of data from 2 registers at the same time, would make this data inconsistent.
In contrast, the C bus can be enabled by more than 1 register at the same time; as a matter of fact, the current value present in the C bus can be written to more than 1 register without  problems.

The reading and writing operations are carried out in 1 clock cycle.

The MBR register is a readonly register, and it contains 2 control lines. Since it is an 8-bit register, its output is connected to the least significant 8 bits of the B bus. It can be set to provide its output in 2 ways:

 2's complement (MBR): all the remaining 24 bits of the B bus are set to 1, if it's a negative number, or they are set to 0, if it's a positive number (sign extension).
 Without complement (MBRU): the remaining 24 bits (of 32 total) are set to 0.

ALU 

The ALU (or arithmetic logic unit) has the following input, output and control lines:

 2 32-bit input lines: one for the B bus and one for the bus that is connected directly to the H register.
 1 32-bit output line, which is connected directly to the shifter.
 6 control lines aimed to select which operation to perform.
 2 other output lines for the status flags N (negative) and Z (zero).

Shifter 

The shifter contains a 32-bit input and output. The output is connected directly to the C bus. The shifter is used to perform logical and arithmetic shift operations, by simply setting respectively the control signal SLL8 (Shift Left Logical) and SRA1 (Shift Right Arithmetic).

External links 

 Article about implementing an Mic-1 virtual Machine in VHDL
 mic1, an open source MIC-1 simulator, including MAL and IJVM assemblers
 emuMIC open source, free and animated MIC-1 emulator, developed by students of the University of Catania (for Windows, Mac and Linux)
 Mic1MMV, the MIC-1 simulator included in the 5th edition of "Structured Computer Organization" by Andrew S. Tanenbaum
 mic1 another open source MIC-1 simulator written by UMass Lowell students, which includes an assembler and microcode compiler

Instruction set architectures
Educational abstract machines
XMT. XMT can refer to:

 Extensible MPEG-4 Textual Format, an XML-based file format for storing MPEG-4 data in a way suitable for further editing
 Explicit multi-threading, a parallel computing paradigm designed around the parallel random-access machine
 Cray XMT - a multithreaded supercomputing architecture, the successor to the Cray MTA-2
 8-hydroxyfuranocoumarin 8-O-methyltransferase, an enzyme
Campus network. A campus network, campus area network, corporate area network or CAN is a computer network made up of an interconnection of local area networks (LANs) within a limited geographical area. The networking equipments (switches, routers) and transmission media (optical fiber, copper plant, Cat5 cabling etc.) are almost entirely owned by the campus tenant / owner: an enterprise, university, government etc. A campus area network is larger than a local area network but smaller than a metropolitan area network (MAN) or wide area network (WAN).

University campuses
College or university campus area networks often interconnect a variety of buildings, including administrative buildings, academic buildings, laboratories, university libraries, or student centers, residence halls, gymnasiums, and other outlying structures, like conference centers, technology centers, and training institutes.

Early examples include the Stanford University Network at Stanford University, Project Athena at MIT, and the Andrew Project at Carnegie Mellon University.

Corporate campuses
Much like a university campus network, a corporate campus network serves to connect buildings. Examples of such are the networks at Googleplex and Microsoft's campus. Campus networks are normally interconnected with high speed Ethernet links operating over optical fiber such as gigabit Ethernet and 10 Gigabit Ethernet.

Area range
The range of CAN is 1 km to 5 km. If two buildings have the same domain and they are connected with a network, then it will be considered as CAN only. Though the CAN is mainly used for corporate campuses so the  link will be high speed.

References

Metropolitan area networks
Computer networks
Flexural rigidity. Flexural rigidity is defined as the force couple required to bend a fixed non-rigid structure by one unit of curvature, or as the resistance offered by a structure while undergoing bending.

Flexural rigidity of a beam

Although the moment  and displacement  generally result from external loads and may vary along the length of the beam or rod, the flexural rigidity (defined as ) is a property of the beam itself and is generally constant for prismatic members. However, in cases of non-prismatic members, such as the case of the tapered beams or columns or notched stair stringers, the flexural rigidity will vary along the length of the beam as well. The flexural rigidity, moment, and transverse displacement are related by the following equation along the length of the rod, :

where  is the flexural modulus (in Pa),  is the second moment of area (in m4),  is the transverse displacement of the beam at x, and  is the bending moment at x. The flexural rigidity (stiffness) of the beam is therefore related to both , a material property, and , the physical geometry of the beam. If the material exhibits Isotropic behavior then the Flexural Modulus is equal to the Modulus of Elasticity (Young's Modulus).

Flexural rigidity has SI units of Pa·m4 (which also equals N·m2).

Flexural rigidity of a plate (e.g. the lithosphere)

In the study of geology, lithospheric flexure affects the thin lithospheric plates covering the surface of the Earth when a load or force is applied to them. On a geological timescale, the lithosphere behaves elastically (in first approach) and can therefore bend under loading by mountain chains, volcanoes and other heavy objects. Isostatic depression caused by the weight of ice sheets during the last glacial period is an example of the effects of such loading.

The flexure of the plate depends on:

 The plate elastic thickness (usually referred to as effective elastic thickness of the lithosphere).
 The elastic properties of the plate
 The applied load or force

As flexural rigidity of the plate is determined by the Young's modulus, Poisson's ratio and cube of the plate's elastic thickness, it is a governing factor in both (1) and (2).

Flexural Rigidity

 = Young's Modulus

 = elastic thickness (~5–100 km)

 = Poisson's Ratio

Flexural rigidity of a plate has units of Pa·m3, i.e. one dimension of length less than the same property for the rod, as it refers to the moment per unit length per unit of curvature, and not the total moment. I is termed as moment of inertia. J is denoted as 2nd moment of inertia/polar moment of inertia.

See also
 Bending stiffness
 Lithospheric flexure

References

Solid mechanics

de:Biegesteifigkeit