omniomni/omni-engineering huggingface dataset:
Pechmann condensation. The Pechmann condensation is a synthesis of coumarins, starting from a phenol and a carboxylic acid or ester containing a β-carbonyl group.  The condensation is performed under acidic conditions.  The mechanism involves an esterification/transesterification followed by attack of the activated carbonyl ortho to the oxygen to generate the new ring.  The final step is a dehydration, as seen following an aldol condensation. It was discovered by the German chemist Hans von Pechmann
.

Mechanism 
To synthesize coumarin derivatives, β-ketoesters can be condensed with phenols under acidic conditions. In this case, a transesterification reaction occurs first with the formation of the phenol ester. This is then followed by ring closure, similar to Friedel-Crafts alkylation.

Examples 
With simple phenols, the conditions are harsh, although yields may still be good.

With highly activated phenols such as resorcinol, the reaction can be performed under much milder conditions.  This provides a useful route to umbelliferone derivatives:

For coumarins unsubstituted at the 4-position, the method requires the use of formylacetic acid or ester.  These are unstable and not commercially available, but the acid may be produced in situ from malic acid and sulfuric acid above 100 °C.  As soon as it forms, the formylacetic acid performs the Pechmann condensation.  In the example shown, umbelliferone itself is produced, albeit in low yield:

Mechanistic studies
The mechanism of the reaction has been studied in details with theoretical treatment.

The study shown that reaction takes place on oxo-form, and not on enolic-form. Three different oxo-routes have been proposed.

Simonis chromone cyclization
In a variation the reaction of phenols and beta-ketoesters and phosphorus pentoxide yields a chromone. This reaction is called Simonis chromone cyclization. The ketone in the ketoester is activated by P2O5 for reaction with the phenol hydroxyl group first, the ester group in it is then activated for electrophilic attack of the arene.

See also 
Aldol condensation
Kostanecki acylation
Perkin reaction

References 

Oxygen heterocycle forming reactions
Condensation reactions
Name reactions
Object-oriented role analysis and modeling. Object-oriented role analysis and modeling (OOram) is a method, based on the concept of role, for performing object-oriented modeling.

Originally (1989) coined Object Oriented Role Analysis, Synthesis and Structuring (OORASS), the method focuses on describing patterns of interaction without connecting the interaction to particular objects/instances. OOram was originally developed by Trygve Reenskaug (1996), a professor at the University of Oslo and the founder of the Norwegian IT company Taskon.  The use of "roles" in OOram is similar in application to that of agent-oriented programming.

Enterprise models created according to OOram may have a number of views, with each view presenting certain aspects of a model. The following ten views are proposed:
 Area of concern view: Textual description of a phenomenon represented in the role model.
 Stimulus-response view: Describes how environment roles may trigger activities in the organization (stimulus), together with the effect (response).
 Role list view: List describing all roles of a role model together with attributes and textual explanation.
 Semantic view: Describes meaning of roles and relationships between roles.
 Collaboration view: Describes patterns of roles and message paths.
 Interface view: Describes all messages that can be sent along a message path.
 Scenario view: Provides a sample sequence of messages flowing between roles (a concrete example).
 Process view: Describes data flow between roles and associated activities performed by the roles.
 State diagram view: For each role, the legal states can be described together with messages that trigger transitions.
 Method specification view: Describes what messages to send for each method belonging to a role. May also specify procedures to perform.

OOram suggests a varied mix of formal and informal notations and languages for representing and communicating models. Which view to use depends upon the needs in a particular situation.

See also 
 Object modeling language
 View model
 Unified modeling language
 i*

References

Further reading 
 
 Rebecca J. Wirfs-Brock and Ralph E. Johnson (1990). Surveying Current Research in Object-Oriented Design. Communications of the ACM, vol. 33, no. 9 (September 1990), pp. 105–124. OORASS on pp. 113–116.

Object-oriented programming
Anisodesmic crystal. An anisodesmic crystal (sometimes anisodemic crystal) is a crystal containing bonds with differing electrostatic valencies. An example is anhydrite. All other crystals are known as isodesmic crystals (or isodemic) and examples include diamond and halite. These terms are of particular importance when discussing the structural chemistry of minerals.

Overview
The electrostatic valency is a measure of the strength of bonds, being the valence charge divided by the coordination number. Linus Pauling's second rule of ionic bonding, the Electrostatic Valence Principle states, "An ionic structure will be stable to the extent that the sum of the strengths of the electrostatic bonds that reach an anion equals the charge on that anion."

When there is more than one type of bonding in a crystal, strongly anisotropic physical properties can result such as those of graphite. Many other substances have anisotropic physical properties. Such properties are directly related to the atomic structures of the substances. Conversely, halite is an example of an isotropic crystal with equal hardness in all directions.

See also
 Crystal cluster
 Colloidal crystal
 Cryptocrystalline

External links
Mineral Crystals
Healing Crystals

Crystals
Enthalpy of atomization. In chemistry, the enthalpy of atomization (also atomisation in British English) is the enthalpy change that accompanies the total separation of all atoms in a chemical substance either an element or a compound. This is often represented by the symbol  or  All bonds in the compound are broken in atomization and none are formed, so enthalpies of atomization are always positive. The associated standard enthalpy is known as the standard enthalpy of atomization, /(kJ mol−1), at 298.15 K (or 25 degrees Celsius) and 100 kPa.

Definition
Enthalpy of atomization is the amount of enthalpy change when bonds of the compound  are broken and the component atoms are separated into single atoms ( or monoatom).

Enthalpy of atomization is denoted by the symbol ΔHat. The enthalpy change of atomization of gaseous H2O is, for example, the sum of the HO–H and H–OH bond dissociation enthalpies.

The enthalpy of atomization of an elemental solid is exactly the same as the enthalpy of sublimation for any elemental solid that becomes a monatomic gas upon evaporation.

When a diatomic element is converted to gaseous atoms, only half a mole of molecules will be needed, as the standard enthalpy change is based purely on the production of one mole of gaseous atoms.

See also
 Ionization energy
 Electron gain enthalpy

References

Enthalpy
ECI Telecom. ECI Telecom Ltd is an Israel-based manufacturer of telecommunications equipment that provides packet optical transport products,  software-defined networking applications, cybersecurity and professional services.

History 
The Electronics Corporation of Israel (ECI) was founded in 1961. It specialized in telephone transmission products that manipulated the signals carried on telephone lines. The Electronics Corporation of Israel became ECI Telecom in 1981, and had its first trading on NASDAQ in 1982. Since that time, ECI has undergone a number of mergers and acquisitions.  An acquisition in 2007 by the Swarth Group and the Ashmore Group, private equity firms, making ECI a private company once again.

In November 2019, Ribbon Communications agreed to acquire ECI Telecom, through a merger, for $486 million.

ECI serves carriers and service providers in various sectors: cable/multiple system operators, wireless/cellular service providers, utilities, carrier of carriers, data centers, government and defense entities.. 
It markets multi-play services, business services, voice services, cellular backhaul, utelco and network security.

Facebook in its phase five has given transport core network deployment to Ciena and worldwide metro packet network deployment to ECI telecom which will be completed by 2022.

ECI has over 3,000 employees with offices in over 20 countries and development centers in India, China, and Israel.

Former holdings and spin-offs 

 ECtel - provider of revenue assurance software sold to cVidya in 2010.
 Veraz Networks - provider of Softswitch technology merged with NexVerse Networks to form a new company called Veraz Networks in 2002. 
 InnoWave ECI Wireless Systems Ltd - sold to Alvarion in 2003
 Celtro communication Ltd - provider of cellular network Backhaul (telecommunications) optimization and compression technology, worked as an independent business unit within the NGTS division was spun off to a private investor group led by the Momentum Venture Management fund in 2003.

See also
Economy of Israel

References

External links
Company website
Acquisition of the company in 2007
ECI Telecom history

Technology companies established in 1961
Manufacturing companies of Israel
Telecommunications equipment vendors
Telecommunications companies of Israel
Companies based in Petah Tikva
2007 mergers and acquisitions
Elastica theory. The elastica theory is a theory of mechanics of solid materials developed by Leonhard Euler that allows for very large scale elastic deflections of structures. 
Euler (1744) and Jakob Bernoulli developed the theory for elastic lines (yielding the solution known as the elastica curve) and studied buckling. Certain situations can be solved exactly by elliptic functions. Later elastica theory was generalized together by the Cosserat brothers François and Eugene  into a geometric theory with intrinsic directions at each point (1907).

Elastica theory is an example of bifurcation theory. For most boundary conditions several solutions exist simultaneously.

When small deflections of a structure are to be analyzed, elastica theory is not required and an approximate solution may be found using the simpler linear elasticity theory or (for 1-dimensional components) beam theory.

A modern treatise of the planar elastica with full account of bifurcation and instability has been recently presented by Bigoni.

See also
 Finite strain theory

References

A Treatise on the Mathematical Theory of Elasticity by Augustus Edward Hough Love
 
 Web site of Gert van der Heijden.
  A PhD thesis on elastic rods by Geoff Goss, June 2003.
The elastica: a mathematical history by Raph Levien (about the curve)

Continuum mechanics
Nectaris. Nectaris, occasionally released as Military Madness, is a series of sci-fi-themed, hex map turn-based strategy games for a variety of systems. The games were developed by Hudson Soft. The company was absorbed by Konami in 2012, and as a result Konami owns the rights to the series.

Games in the series include:
 Nectaris / Military Madness (PC-Engine / TurboGrafx-16, 1989)
 Nectaris (PC 9800 & X68000, 1992)
 Neo Nectaris / Military Madness 2 (PC-Engine CD, 1994)
 Nectaris (PC DOS, 1995)
 Nectaris (Windows 95, 1997)
 Nectaris GB (Game Boy, February 1998)
 Nectaris (PlayStation, 1998), (PlayStation Network, 2008)
 Nectaris Cellular (i-mode, 2003)
 Military Madness (US cellphone (Verizon) v1.1)
 Military Madness: Nectaris (WiiWare, Xbox Live Arcade, PlayStation Network, 2009)
 Military Madness: Neo Nectaris (iPhone, 2010)

References

External links
 Base Nectaris, a fan site (Military Madness FAQ)
 Compmike's Nectaris Walkthrough

Computer wargames
DOS games
Hudson Soft games
Konami franchises
Game Boy games
NEC PC-9801 games
PlayStation (console) games
PlayStation Network games
X68000 games
Turn-based tactics video games
TurboGrafx-CD games
TurboGrafx-CD-only games
Video games scored by Chris Huelsbeck
Video games scored by Jun Chikuma
Windows games
Embedded C++. Embedded C++ (EC++) is a dialect of the C++ programming language for embedded systems. It was defined by an industry group led by major Japanese central processing unit (CPU) manufacturers, including NEC, Hitachi, Fujitsu, and Toshiba, to address the shortcomings of C++ for embedded applications. The goal of the effort is to preserve the most useful object-oriented features of the C++ language yet minimize code size while maximizing execution efficiency and making compiler construction simpler. The official website states the goal as "to  provide embedded systems programmers with a subset of C++ that is easy for the average C programmer to understand and use".

Differences from C++ 
Embedded C++ excludes some features of C++.

Some compilers, such as those from Green Hills and IAR Systems, allow certain features of ISO/ANSI C++ to be enabled in Embedded C++. IAR Systems calls this "Extended Embedded C++".

Compilation 
An EC++ program can be compiled with any C++ compiler. But, a compiler specific to EC++ may have an easier time doing optimization.

Compilers specific to EC++ are provided by companies such as:
IAR Systems
Freescale Semiconductor, (spin-off from Motorola in 2004 who had acquired Metrowerks in 1999)
Tasking Software, part of Altium Limited
Green Hills Software

Criticism 

The language has had a poor reception with many expert C++ programmers. In particular, Bjarne Stroustrup says, "To the best of my knowledge EC++ is dead (2004), and if it isn't it ought to be." In fact, the official English EC++ website has not been updated since 2002. Nevertheless, a restricted subset of C++ (based on Embedded C++) has been adopted by Apple Inc. as the exclusive programming language to create all I/O Kit device drivers for Apple's macOS, iPadOS and iOS operating systems of the popular Macintosh, iPhone, and iPad products. Apple engineers felt the exceptions, multiple inheritance, templates, and runtime type information features of standard C++ were either insufficient or not efficient enough for use in a high-performance, multithreaded kernel.

References

External links 
 
 Background and Objectives of the Embedded C++ Specification Development
 Embedded C++ Yields Faster Smaller Code, John Carbone (Embedded.com), June 19, 1998
 Building Bare-Metal ARM Systems with GNU: Part 1 - Getting Started, Miro Samek, Quantum Leaps, June 26, 2007
 Technical Report on C++ Performance, by WG 21 of ISO Subcommittee SC 22

C++ programming language family
C++
Hardware description languages
Embedded systems
Shaped Sonic Boom Demonstration. The NASA Shaped Sonic Boom Demonstration, also known as the Shaped Sonic Boom Experiment, was a two-year program that used a Northrop F-5E with a modified fuselage to demonstrate that the aircraft's shock wave, and accompanying sonic boom, can be shaped, and thereby reduced. The program was a joint effort between NASA's Langley Research Center, Dryden Flight Research Center at Edwards Air Force Base, California and Northrop Grumman.

The program became, at that time (2003), the most extensive study on the sonic boom. After measuring the 1,300 recordings, some taken inside the shock wave by a chase plane, the SSBD demonstrated a reduction in boom by about one-third.  Several of the flights included NASA Dryden's F-15B research testbed aircraft following to measure the F-5E's shock wave signature close-up. During the flights, many shock wave patterns were measured by the F-15B at various distances and orientations from the F-5E.

An unmodified F-5E flew a few seconds behind the demonstration aircraft to provide a baseline sonic boom measurement to validate the reduced boom produced by the demonstrator.

A U.S. Air Force Test Pilot School Blanik L-23 glider carrying a microphone on the left wingtip, and a pressure transducer on the side of the fuselage, flew at a lower altitude of  under the path of the F-5E, which flew at , to record sonic booms in the air. In addition, sonic boom data were gathered on the ground by an array of 42 sensors and recording devices along  under the flight path of the F-5E. Dryden-developed boom amplitude and direction sensors recorded ground-level sonic boom signature data.

The demonstration was initially part of the Quiet Supersonic Platform program funded by Defense Advanced Research Projects Agency (DARPA). Subsequently, the vehicle systems division of NASA's Office of Aeronautics funded the project. Northrop-Grumman Corporation's Integrated Systems Sector in El Segundo, California, modified the U.S. Navy F-5E aircraft into the SSBD aircraft. The aircraft is on display at the Valiant Air Command Warbird Museum at Titusville, Florida.

See also
Supersonic aerodynamics
Whitcomb area rule
Sound barrier
Mach number
 Quiet Spike
 Low Boom Flight Demonstrator
 Gulfstream X-54

References

External links 
 
 
 NASA Dryden Shaped Sonic Boom Demonstration Photo Collection
 "Quieting the Boom: The Shaped Sonic Boom Demonstrator and the Quest for Quiet Supersonic Flight" by Lawrence R. Benson (NASA Aeronautics Book Series)

NASA programs
DARPA
NASA aircraft
Northrop Grumman aircraft
John A. Volpe National Transportation Systems Center. The John A. Volpe National Transportation Systems Center (colloquially, the Volpe Center) in Cambridge, Massachusetts, is a center of transportation and logistics expertise in the Research and Innovative Technology Administration of the United States Department of Transportation (U.S. DOT).

The center's work includes projects that cut across traditional transportation modes and technical disciplines, including the Federal Aviation Administration's Enhanced Traffic Management System (ETMS) and Safety Performance Analysis System (SPAS), and the Federal Motor Carrier Safety Administration's SafeStat Online.

The Center helps federal, state, and local governments, industry, and academia in various areas, including human factors research, system design, implementation and assessment, global tracking, strategic investment and resource allocation, environmental preservation, and organizational effectiveness.

Volpe differs from most federal organizations in that it receives no direct appropriation from Congress. Instead, its roughly $200 million annual budget is funded by fees for its work.

The center is named for John Volpe, a former Massachusetts governor and U.S. Secretary of Transportation.

Location 
Volpe is located on the campus of NASA's former Electronics Research Center in Cambridge, Massachusetts, across the Charles River from Boston, across the street from the Massachusetts Institute of Technology (MIT), and next to the Kendall/MIT MBTA Red Line subway stop.

Redevelopment 
In January 2017, MIT signed an agreement with the U.S. General Services Administration (GSA) to redevelop the John A. Volpe National Transportation Systems Center, with the state aim of turning the 14-acre parcel into a more vibrant mixed-use site.

In October 2017, the Cambridge City Council approved MIT’s rezoning petition for the site and a team of architects and landscape planners have been working to imagine a new home for the Volpe Center.

See also
Aircraft Situation Display to Industry

References

External links
 

United States Department of Transportation
United States Department of Transportation agencies
Organizations based in Cambridge, Massachusetts
Iron(III) bromide. Iron(III) bromide is the chemical compound with the formula FeBr3.  Also known as ferric bromide, this red-brown odorless compound is used as a Lewis acid catalyst in the halogenation of aromatic compounds. It dissolves in water to give acidic solutions.

Structure, synthesis and basic properties
FeBr3 forms a polymeric structure featuring six-coordinate, octahedral Fe centers.  Although inexpensively available commercially, FeBr3 can be prepared by treatment of iron metal with bromine:
2 Fe  +  3 Br2  →  2 FeBr3

Above 200 °C, FeBr3 decomposes to ferrous bromide:
2FeBr3  →  2FeBr2  +  Br2
Iron(III) chloride is considerably more stable, reflecting the greater oxidizing power of chlorine.   FeI3 is not stable, as iron(III) will oxidize iodide ions.

Uses
Ferric bromide is occasionally used as an oxidant in organic chemistry, e.g. for the conversion of alcohols to ketones.  It is used as a Lewis acidic catalyst for bromination of aromatic compounds.  For the latter applications, it is often generated in situ.

See also
Iron(II) bromide, the lower bromide of iron

References

Iron(III) compounds
Bromides
Metal halides
Supramolecular electronics. Supramolecular electronics is the experimental field of supramolecular chemistry that bridges the gap between molecular electronics and bulk plastics in the construction of electronic circuitry at the nanoscale. In supramolecular electronics, assemblies of pi-conjugated systems on the 5 to 100 nanometer scale are prepared by molecular self-assembly with the aim to fit these structures between electrodes. With single molecules as researched in molecular electronics at the 5 nanometer scale this would be impractical. Nanofibers can be prepared from polymers such as polyaniline and polyacetylene. Chiral oligo(p-phenylenevinylene)s self-assemble in a controlled fashion into (helical) wires. An example of actively researched compounds in this field are certain coronenes.

References 

Electronics
Molecular electronics
Nanoelectronics
Thermal diffusion. Thermal diffusion may refer to:
 A thermal force on a gas due to a temperature gradient, also called thermal diffusion or Thermal transpiration.
 It is used to drive a gas pump with no moving parts called a Knudsen pump.
 It is the currently accepted theory for the rotation of the Crookes radiometer.
 Diffusion in a temperature gradient, also called thermodiffusion or thermophoresis.
 It can be used as an obsolete method of making enriched uranium (see enriched uranium § thermal diffusion).
 Thermal diffusion can be used to measure fluid flow, including perfusion and rCBF at one location over time.
 Brownian motion (at a constant non-zero absolute temperature).
See also:
 Molecular diffusion
 Heat conduction (i.e., diffusion of heat)
Mesityl oxide. Mesityl oxide is a α,β-unsaturated ketone with the formula CH3C(O)CH=C(CH3)2. This compound is a colorless, volatile liquid with a honey-like odor.

Synthesis
It is prepared by the aldol condensation of acetone to give diacetone alcohol, which readily dehydrates to give this compound.

Phorone and isophorone may be formed under the same conditions. Isophorone originates via a Michael addition:

Phorone is formed by continued aldol condensation:

Uses
Mesityl oxide is used as a solvent and in the production of methyl isobutyl ketone by hydrogenation:

Further hydrogenation gives 4-methyl-2-pentanol (methyl isobutyl carbinol).

Dimedone is another established use of mesityl oxide.

References

External links
IPCS INCHEM Description
CDC - NIOSH Pocket Guide to Chemical Hazards

Enones
Ketone solvents
Boeing X-46. The Boeing X-46 was a proposed unmanned combat air vehicle (UCAV) that was to be developed in conjunction with the United States Navy and DARPA as a naval carrier-based variant of the Boeing X-45 UCAV being developed for the U.S. Air Force. Two contracts for technology demonstrators were awarded in June 2000, to Boeing for the X-46A and to Northrop Grumman for the X-47A.

However, in April 2003, the Air Force and the Navy efforts were formally combined under the joint DARPA/USAF/Navy J-UCAV program, later renamed J-UCAS (Joint Unmanned Combat Air Systems), and the X-46 program was terminated as redundant.

A Navy-only N-UCAS demonstrator program started in the summer of 2006.  Boeing will use material developed for the X-46 and X-45 to propose the X-45N as a naval UCAV demonstrator.

References

External links

 Boeing X-45 / X-46 Page

X-46
Unmanned aerial vehicles of the United States
Single-engined jet aircraft
Cancelled military aircraft projects of the United States
DARPA