omniomni/omni-engineering huggingface dataset:
Chandy–Lamport algorithm. The Chandy–Lamport algorithm is a snapshot algorithm that is used in distributed systems for recording a consistent global state of an asynchronous system. It was developed by and named after Leslie Lamport and K. Mani Chandy.

History
According to Leslie Lamport's website, the snapshot algorithm was described when they visited Chandy, who was at the University of Texas (Austin). He posed the problem over dinner, but they had too much wine to think about it. The next morning, while Lamport was in the shower, he came up with the solution. When he arrived at Chandy's office, he was waiting for him with the same solution. They considered the algorithm to be the straightforward application from the basic ideas of article 27, titled "Time, Clocks and the Ordering of Events in a Distributed System".

Definition
The assumptions of the algorithm are as follows:
 There are no failures and all messages arrive intact and only once
 The communication channels are unidirectional and FIFO ordered
 There is a communication path between any two processes in the system
 Any process may initiate the snapshot algorithm
 The snapshot algorithm does not interfere with the normal execution of the processes
 Each process in the system records its local state and the state of its incoming channels

The algorithm works using marker messages. Each process that wants to initiate a snapshot records its local state and sends a marker on each of its outgoing channels. All the other processes, upon receiving a marker, record their local state, the state of the channel from which the marker just came as empty, and send marker messages on all of their outgoing channels. If a process receives a marker after having recorded its local state, it records the state of the incoming channel from which the marker came as carrying all the messages received since it first recorded its local state.

Some of the assumptions of the algorithm can be facilitated using a more reliable communication protocol such as TCP/IP. The algorithm can be adapted so that there could be multiple snapshots occurring simultaneously.
..///

Algorithm
The Chandy–Lamport algorithm works like this:

 The observer process (the process taking a snapshot):
 Saves its own local state
 Sends a snapshot request message bearing a snapshot token to all other processes
 A process receiving the snapshot token for the first time on any message:
 Sends the observer process its own saved state
 Attaches the snapshot token to all subsequent messages (to help propagate the snapshot token)
 When a process that has already received the snapshot token receives a message that does not bear the snapshot token, this process will forward that message to the observer process.  This message was obviously sent before the snapshot “cut off” (as it does not bear a snapshot token and thus must have come from before the snapshot token was sent out) and needs to be included in the snapshot.

From this, the observer builds up a complete snapshot: a saved state for each process and all messages “in the ether” are saved.

References

Distributed algorithms
Happened-before. In computer science, the happened-before relation (denoted: ) is a relation between the result of two events, such that if one event should happen before another event, the result must reflect that, even if those events are in reality executed out of order (usually to optimize program flow). This involves ordering events based on the potential causal relationship of pairs of events in a concurrent system, especially asynchronous distributed systems. It was formulated by Leslie Lamport.

The happened-before relation is formally defined as the least strict partial order on events such that:
 If events  and  occur on the same process,  if the occurrence of event  preceded the occurrence of event .
 If event  is the sending of a message and event  is the reception of the message sent in event , .

If two events happen in different isolated processes (that do not exchange messages directly or indirectly via third-party processes), then the two processes are said to be concurrent, that is neither  nor  is true. 

If there are other causal relationships between events in a given system, such as between the creation of a process and its first event, these relationships are also added to the definition.
For example, in some programming languages such as Java, C, C++ or Rust, a happens-before edge exists if memory written to by statement A is visible to statement B, that is, if statement A completes its write before statement B starts its read.

Like all strict partial orders, the happened-before relation is transitive, irreflexive (and vacuously, asymmetric), i.e.:
 , if  and , then  (transitivity). This means that for any three events , if  happened before , and  happened before , then  must have happened before .
  (irreflexivity). This means that no event can happen before itself.
  if  then  (asymmetry). This means that for any two events , if  happened before  then  cannot have happened before .

Let us observe that the asymmetry property directly follows from the previous properties: by contradiction, let us suppose that  we have  and . Then by transitivity we have  which contradicts irreflexivity.

The processes that make up a distributed system have no knowledge of the happened-before relation unless they use a logical clock, like a Lamport clock or a vector clock. This allows one to design algorithms for mutual exclusion, and tasks like debugging or optimising distributed systems.

See also
 Race condition
 Java Memory Model
 Lamport timestamps
 Logical clock

Citations

References

Logical clock algorithms
Distributed computing problems
Transitive relations
Industrial data processing. Industrial data processing is a branch of applied computer science that covers the area of design and programming of computerized systems which are not computers as such — often referred to as embedded systems (PLCs, automated systems, intelligent instruments, etc.).  The products concerned contain at least one microprocessor or microcontroller, as well as couplers (for I/O).

Another current definition of industrial data processing is that it concerns those computer programs whose variables in some way represent physical quantities; for example the temperature and pressure of a tank, the position of a robot arm, etc.

Computer engineering
LSE. LSE may refer to:

Education 
 London School of Economics and Political Science, a public research university within the University of London
 Lahore School of Economics, a private university in Lahore, Punjab, Pakistan
 Lincoln Southeast High School, a public government education school located in Lincoln, Nebraska
 Louvain School of Engineering, faculty of engineering science at the University of Louvain (UCLouvain), Belgium

Computing 
  ("Symbolic teaching language"), a computer programming language
 Language-Sensitive Editor, a text editor used on Digital Equipment Corporation's VMS operating system
 Large system extensions, a set of atomic memory operations such as fetch-and-add for the 64-bit ARM (AArch64) architecture
 Latent sector error, an unrecoverable read error on a hard disk drive which has not yet been discovered

Finance 
 Lahore Stock Exchange, now Pakistan Stock Exchange
 London Stock Exchange
 London Stock Exchange Group, the owner group of the London Stock Exchange

Transport 
 La Crosse Regional Airport, Wisconsin, United States (IATA code LSE)
 Luzern–Stans–Engelberg railway line, a mountain railway in Switzerland

Other uses 
 Load serving entity, an electricity demand aggregator in the deregulated market.
 Landing ship, Emergency Repair, a US WW2 Navy ship
 Least-squares estimation, a statistical technique commonly used in data fitting
 Lengua de signos española, Spanish Sign Language
 Logical Sensory Extrovert, a socionics personality type
Crystal Space. Crystal Space is an unmaintained framework for developing 3D applications written in C++ by Jorrit Tyberghein and others.  The first public release was on August 26, 1997.  It is typically used as a game engine but the framework is more general and can be used for any kind of 3D visualization. It is very portable and runs on Microsoft Windows, Linux, UNIX, and Mac OS X.  It is also free and open-source software, licensed under the GNU LGPL-2.0-or-later, and was SourceForge.net's Project of the Month for February 2003. In 2019, one of the project's main developers described it as "effectively dead and has been for a good number of years".

Engine design 
Crystal Space is programmed in object oriented C++. It is very modularly built with a number of more or less independent plugins. The client programs use the plugins, such as the OpenGL 3D renderer, by registering them via Crystal Space's Shared Class Facility (SCF).

Features
Crystal Space has modules for 2D and 3D graphics, sound, collision detection and physics through ODE and Bullet.
Graphics:
OpenGL rendering
Supports hardware acceleration from all major card vendors
Allows use of shaders
Library of common shaders like normal mapping, parallax mapping and hardware skinning
Supports software rendering with limited features
Mesh objects:
Plugin-based mesh system
Triangle-based meshes with frame and bone animation support
Collision detection and dynamics:
ODE and Bullet dynamics
Simplified collision detection when full dynamic simulation is not needed

Reception and usage 
The engine was, for instance, used for the OpenOutcast and PlaneShift projects. It was the Project of the Month on SourceForge in February 2003.

References

External links

  at SourceForge
 Crystal Space engine details and reviews at the Internet Archive

1997 software
Cross-platform software
Free game engines
Free software programmed in C++
Game engines for Linux
Python (programming language)-scriptable game engines
AUI. AUI may stand for:

 Ethernet's Attachment Unit Interface, a 15-pin D-connector
 aUI, a constructed language
 The ICAO code for Ukraine International Airlines, Ukraine
 The National Rail code for Ardlui railway station, United Kingdom 
 Associated Universities, Inc., the corporation that operates the National Radio Astronomy Observatory (NRAO)
 Amiga User International, a monthly magazine dedicated to the Amiga computer
 Al Akhawayn University,  a university located in Ifrane, Morocco
 Adaptive user interface
 Audible user interface, for blind people to use digital devices
 Attentive user interface
 Gold monoiodide, chemical formula AuI

See also

 
 
 
 AUIS (disambiguation)
Chikugo River. The  flows through Kumamoto, Ōita, Fukuoka and Saga prefectures in Japan.  With a total length of , it is the longest river on Kyūshū. It flows from Mount Aso and empties into the Ariake Sea. It is also nicknamed "Tsukushi Jirō". 

The upper reaches of the river are important to forestry, and the middle and lower reaches are important to local agriculture, providing irrigation to some  of rice fields on the Tsukushi Plain. The river is also important to industry, with twenty electrical power plants located along its banks, as well as the major city of Kurume in Fukuoka Prefecture. Recognizing the requirement to satisfy divergent needs of various communities along the river, the Japanese Ministry of Land, Infrastructure, Transport and Tourism designated the Chikugo River (along with six other river systems in Japan) as a "Water Resources Development River System" with a comprehensive utilization plan to develop the river's resources.

The Chikugogawa Onsen Fireworks, held annually on July 28, are the largest fireworks display in Kyūshū. The event has been held since 1650 on the riverbanks at Kurume.

See also 
Chikugo River Lift Bridge

References 
 de Graaf, Rutger. Urban Water in Japan. CRC Press (2008). 
Japan Water Agency map
Chikugogawa Onsen Fireworks

Notes

Rivers of Fukuoka Prefecture
Rivers of Kumamoto Prefecture
Rivers of Ōita Prefecture
Rivers of Saga Prefecture
Kyushu region
Rivers of Japan
Pierre-Simon Girard. Pierre-Simon Girard (4 November 1765 – 30 November 1836) was a French mathematician and engineer, who worked on fluid mechanics.

Girard was born in Caen.  A prodigy who invented a water turbine at the age of ten, he worked as an engineer at the École Nationale des Ponts et Chaussées. He was in charge of planning and construction of the Amiens canal and the Ourcq canal. He collaborated with Gaspard de Prony on the Dictionnaire des Ponts et Chaussées (Dictionary of Bridges and Highways,  1787). He wrote on fluids, and in 1798 he published a monograph, Traité analytique de la résistance des solides on beam theory, including possibly its first history, within the topic of strength of materials. The complicated beam equations were not of practical much use, since he applied Euler's non-linear theory. In 1799, he and other engineers and scientists accompanied Napoleon on his expedition to Egypt. He died in Paris, aged 71.

Important works 
The 1798 monograph Traite Analytique de la Resistance des solides, et des solides d'e'gale Resistance, Auquel on a joint une suite de nouvelles Experiences sur la force, et Velasticite specifique des Bois de Chine et de Sapin was reviewed by Isaac Todhunter, and his editor, Karl Pearson as follows.This work very fitly closes the labours of the 18th century. It is the first practical treatise on Elasticity; and one of the first attempts to make searching experiments on the elastic properties of beams. It is not only valuable as containing the total knowledge of that day on the subject, but also by reason of an admirable historical introduction... The work appears to have been begun in 1787 and portions of it presented to the Academie in 1792. Its final publication was delayed till the experiments on elastic bodies, the results of which are here tabulated, were concluded at Havre.

References

 André Guillerme: Bâtir la ville – révolutions industrielles dans les matériaux de construction. (1995), éd. Champ Vallon. 
 Antoine Picon: L'invention de l'ingenieur moderne. (1992), Presses des Ponts & Chaussées. 
 Stephen Timoshenko: History of strength of materials. 1953, Nachdruck. 1983. 

French civil engineers
École des Ponts ParisTech alumni
Corps des ponts
1765 births
1836 deaths
Scientists from Caen
18th-century French mathematicians
19th-century French mathematicians
French fluid dynamicists
Hopewell Highway Infrastructure. Hopewell Highway Infrastructure Limited (HHI; ), , , previously controlled by Hong Kong tycoon Gordon Wu, was the highway unit of Hong Kong-listed conglomerate Hopewell Holdings Ltd. It is now currently controlled by the Shenzhen Expressway Corporation Limited under the new name Shenzhen Investment Holdings Bay Area Development Company Limited, with the current chairman and executive director being Xiangwen Liao.

HHI had interests in two toll road projects in China, including the Guangzhou-Shenzhen Superhighway, which links the capital of the province of Guangdong to the Hong Kong-Shenzhen border, and another one that is due to be completed by 2004.

It also hopes to make a bid for a stake in a proposed giant bridge project,  Hong Kong-Zhuhai-Macau Bridge, linking Hong Kong to Macau and mainland China.

It raised HK$3.01 billion (US$385.9 million) from its IPO in early August, 2003.

In 11 January 2022, Shenzhen Expressway Corporation Limited, a company listed on the Stock Exchange of Hong Kong and Shanghai Stock Exchange became the controlling shareholder of the Company. The Company was later renamed Shenzhen Investment Holdings Bay Area Development Company Limited.

See also
List of Hong Kong companies

References

External links
Hopewell Highway Infrastructure Limited

Companies listed on the Hong Kong Stock Exchange
Construction and civil engineering companies of Hong Kong
Transport in Hong Kong
Private road operators
Hopewell Holdings
Construction and civil engineering companies established in 2003
2003 establishments in Hong Kong
Chinese companies established in 2003
Chinese companies disestablished in 2022
2022 disestablishments in Hong Kong
Bell XP-52. The Bell XP-52 and subsequent XP-59 were World War II fighter aircraft design projects by the American Bell Aircraft Corporation.

Both projects featured a twin-boom layout with a rear-mounted engine driving pusher contra-rotating propellers.

When the XP-59 project was canceled the designation XP-59A was used as a cover for a secret jet fighter prototype, which would enter production as the P-59 Airacomet.

XP-52

The XP-52 design was begun by the Bell Company in 1940, separate from the R-40C competition, under the Air Material Command designator MX-3.

The short fuselage carried a piston engine in the rear, driving a pair of contra-rotating propellers in a pusher configuration. The wings were swept back at an angle of 20 degrees, with a horizontal stabilizer mounted behind the propeller on twin booms running back from the wings. The fuselage was unusually streamlined, being round and barrel-shaped, with the forward-located pilot's cockpit fully faired-in to its lines and the nose ending in a round air intake which was ducted back internally to the engine. The undercarriage was a tricycle arrangement, with the main wheels retracting into the tailbooms. Propulsion was to be provided by the experimental Continental XIV-1430-3 inverted V-12 engine.

The XP-52 was canceled in October 1940 because the XIV-1430 engine ran into technical difficulties. Bell submitted a similar design to the US Navy as the Model 19, but this too was never built.

XP-59
Although generally similar in layout to the XP-52, the XP-59 was slightly larger and heavier, and was to be powered by a Pratt and Whitney R-2800-23 engine of . Two prototypes were ordered in February 1941.

On 3 October 1941 the contract for Bell's first jet fighter was signed. The prototype was designated the XP-59A and it would enter production as the P-59 Airacomet. The original XP-59 was canceled on November 25, 1941 because Bell itself was pre-occupied with development of the Bell P-63 Kingcobra.

See also

References

External links
 Bell XP-52

P-052
Cancelled military aircraft projects of the United States
Twin-boom aircraft
Single-engined pusher aircraft
Aircraft with contra-rotating propellers
Low-wing aircraft
Aircraft with retractable tricycle landing gear
1940s United States fighter aircraft
Better Living Through Chemistry. The phrase "Better Living Through Chemistry" (BLTC) is a variant of a DuPont advertising slogan, "Better Things for Better Living...Through Chemistry". DuPont adopted it in 1935 and it was their slogan until 1982 when the "Through Chemistry" part was dropped. Since 1999, their slogan has been "The miracles of science".

The phrase "Better Living Through Chemistry" was used on products that were not affiliated with DuPont to circumvent trademark infringement. This transmutation is now more commonly used than the original. This statement is used for commentary on several different topics, from the promotion of prescription or recreational drugs, to the praise of chemicals and plastics, to the sarcastic criticism of the same.

DuPont used the "Better Living Through Chemistry" slogan not to promote particular products, but to change viewers' opinions about the role of business in society. In the words of DuPont's advertising director, Charles Hackett, the advertisements sought to address "unspoken fears of bigness in business", which were based on "an emotional rather than a rational foundation".

The phrase has since been used in popular culture as the name of a film and of music albums, sometimes as a euphemistic reference to recreational drug use.

References

External links 
  DuPont - Better Things...

1935 quotations
American advertising slogans
DuPont
Self-healing ring. A self-healing ring, or SHR, is a telecommunications term for loop network topology, a common configuration in telecommunications transmission systems.  Like roadway and water distribution systems, a loop or ring is used to provide redundancy. SDH, SONET and WDM systems are often configured in self-healing rings.

Description
The system consists of a ring of bidirectional links between a set of stations, typically using optical fiber communications. 
In normal use, traffic is dispatched in the direction of the shortest path towards its destination.
In the event of the loss of a link, or of an entire station, the two nearest surviving stations "loop back" their ends of the ring. In this way, traffic can still travel to all surviving parts of the ring, even if it has to travel "the long way round".

A second break in the ring may divide it into two sub-rings, but in such a case each sub-ring will remain functional.

Advantages
Self-healing rings offer high levels of resilience at low cost, since it is often geographically easy to take multiple paths across the landscape and link them up into a ring with very little extra fiber length.

Recent submarine communications cables are typically built in pairs to function as a self-healing ring. Very high resilience systems are typically built on interconnected meshes of self-healing rings.

Another example of a self-healing ring network technology is the FDDI local-area network. Resilient Packet Ring is a new technology for packet-switched self-healing ring networks.

See also
 Redundancy (engineering)

Telecommunications equipment
Polyphase coil. Polyphase coils are electromagnetic coils  connected together in a polyphase system such as a generator or motor.  In modern systems, the number of phases is usually three or a multiple of three. Each phase carries a sinusoidal alternating current whose phase is delayed relative to one of its neighbours and advanced relative to its other neighbour. The phase currents are separated in time evenly within each period of the alternating current. For example, in a three-phase system, the phases are separated from each other by one-third of the period.

Coil construction
Like all coils used in electrical machinery, polyphase coils (made from insulated conducting wire) are wound around ferromagnetic armatures with radial projections and maximum core-surface exposure to the magnetic field.

The windings are physically separated around the circumference of an electrical machine. The result of such an arrangement is a rotating magnetic field that is used to convert electrical power to rotary mechanical work, or vice versa.

Polyphase motors and generators
Compared to single-phase motors and generators, polyphase motors are simpler, because they do not require external circuitry (using capacitors and inductors) to produce a starting torque. Polyphase machines can deliver constant power over each period of the alternating current, eliminating the pulsations found in a single-phase machine as the current passes through zero amplitude.

History
The use of polyphase coils in electrical power systems was pioneered by the engineers Nikola Tesla, Galileo Ferraris, and Michail Dolivo-Dobrovolsky.

See also
 Alternator
 Induction motor
 Single-phase generator

Electric transformers
Electromagnetic coils
AC power
Source-code compatibility. Source-code compatibility (source-compatible) means that a program can run on computers (or operating systems), independently of binary-code compatibility and that the source code is needed for portability.

The source code must be compiled before running, unless the computer used has an interpreter for the language at hand. The term is also used for assembly language compatibility, where the source is a human-readable form of machine code that must be converted into numerical (i.e. executable) machine code by an assembler. This is different from binary-code compatibility, where no recompilation (or assembly) is needed.

Source compatibility is a major issue in the developing of computer programs. For example, most Unix systems are source-compatible, as long as one uses only standard libraries. Microsoft Windows systems are source-compatible across one major family (the Windows NT family, from NT 3.1 through Windows 11, or the family that includes Windows 95, Windows 98, and Windows Me), with partial source compatibility between the two families.

See also 
 Backward compatibility
 Source upgrade

References 

Backward compatibility
Source code