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Hard-paste porcelain

Hard-paste porcelain is a hard ceramic that was originally made from a compound of the feldspathic rock petuntse and kaolin fired at very high temperature. It was first made in China around the 9th century.

Historically, “hard-paste” referred to the Asian porcelains that had been prepared from the aforementioned raw materials. The secret of its manufacture was not known in Europe until 1709, when Böttger of Meissen, Germany discovered the formula. Despite attempts to keep it secret, the process spread to other German ceramic factories and eventually throughout Europe. Hard-paste, or just hard porcelain, now chiefly refers to formulatons prepared from mixtures of kaolin, feldspar and quartz. Other raw materials can also be used and these include porcelain and pottery stones. These are the same as petunse, but this name has long fallen out of use. Hard-paste porcelain is now differentiated from soft-paste porcelain mainly by the firing temperature, with the former being higher to around 1400 degrees Celsius and the latter to around 1200 degrees Celsius.<ref> Singer, F. and Singer, S.S., Industrial Ceramics (Chapman Hall, 1963) .</ref><ref>Rado, Paul, An Introduction To The Technology Of Pottery (Pergamon Press, 1988) .</ref> Depending on the raw materials and firing methods used, hard-paste porcelain can also resemble stoneware or earthenware. Hard-paste porcelain can be utilized to make porcelain bisque, a particularly hard type of porcelain. It is a translucent and bright, white ceramic. With it being almost impermeable to water it is unnecessary to glaze the body. Manufactures that use hard-paste porcelain for their products include Lladro, Hummel, and Precious Moments.


See also

  • Soft-paste porcelain
  • Bone china


References

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External links

  • Teapots.net. “The Invention of Hard-Paste Porcelain”. History of Teapots. http://www.teapots.net/porcelain.html
  • ThePotteries.org. “Hard paste porcelain”. Types and Examples of Pottery. http://www.thepotteries.org/types/hardpaste.htm

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Neptune’s Staircase

Neptune’s Staircase is a staircase lock comprising eight locks on the Caledonian Canal. It is the longest staircase lock in the United Kingdom, and lifts boats 64 feet (19.5 metres). The locks were originally hand-powered, but have been converted to hydraulic operation.
The base plinths of the original capstans are still present, although the capstans themselves are now gone.

The current lock gates weigh 22 tons each, and require a team of three lock-keepers (at minimum) to run the staircase.

It is usual for them to operate on an “Efficiency Basis”, that is the keepers try to either fill each cut with boats on the lift or drop, or to allow for passing, ie a dropping craft to pass a rising craft on the same fill/empty cycle.

It is one of the biggest staircases in Britain, and is kept by British Waterways.

It is located at Banavie, near Fort William just north of Loch Linnhe.

The structure was designed by Thomas Telford.

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Chubb Locks

The Chubb Locks subsidiary of the Assa Abloy Group is a British manufacturer of high security locking systems for residential and commercial applications.

Chubb was started as a ship’s ironmonger by Charles Chubb in Winchester, England and then moved to Portsmouth, England in 1804.

Chubb moved the company into the locksmith business in 1818 in Wolverhampton. The company worked out of a number of premises in Wolverhampton including the purpose built factory on Railway Street now still known as the Chubb Building. His brother Jeremiah Chubb then joined the company and they sold Jeremiah’s patented detector lock

In 1823 the company was awarded a special license by George IV and later became the sole supplier of locks to the General Post Office and a supplier to His Majesty’s Prison Service.

In 1835 they received a patent for a burglar-resisting safe and opened a safe factory in London in 1837.

In 1851 they designed a special secure display case for the Koh-i-Noor diamond for its appearance at the Great Exhibition.

In 1984 the company was purchased by Racal, who sold it in 1997 to Williams Plc. In August 2000, they were sold to Assa Abloy.


Cultural references

  • Chubb Locks is mentioned in Alan Hollinghurst’s 2005 novel, The Line of Beauty (in the very last pages).
  • Irene Adler’s manor in The Adventures of Sherlock Holmes is secured by a Chubb lock.


See also

  • Baron Hayter


External links

  • Official website

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Relative effectiveness factor

Relative effectiveness factor (R.E. factor) is a measurement of an explosive’s power for military demolitions purposes. It is used to compare an explosives effectiveness relative to TNT by weight only. This is so engineers can substitute one explosive for another when they are figuring out blasting equations that are designed for TNT. For example, If a timber cutting charge requires 1kg of TNT to work, it would take 0.6kg of PETN or 2.4kgs of Ammonium Nitrate to have the same effect.

Some examples of RE factors include

Ammonium nitrate = 0.42
Black powder = 0.55
TNT = 1.00
C-4 = 1.34
Nitroglycerin = 1.50
RDX = 1.60
PETN = 1.66
Semtex = 1.66
HMX = 1.70
Hexanitrohexaazaisowurtzitane = 2.04
Octanitrocubane = 2.7


See also

  • Brisance

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Conservative two-phase locking

In computer science, conservative two-phase locking (C2PL) is a locking method used in DBMS and relational databases.

Conservative 2PL prevents deadlocks.

The difference between 2PL and C2PL is that C2PL’s transactions obtain all the locks they need before the transactions begin. This is to ensure that a transaction that already holds some locks will not block waiting for other locks.

In heavy lock contention, C2PL reduces the time locks are held on average, relative to 2PL and Strict 2PL, because transactions that hold locks are never blocked.

In light lock contention, C2PL holds more locks than is necessary, because it is hard to tell what locks will be needed in the future, thus leads to higher overhead.

Also, a transaction will not even obtain any locks if it cannot obtain all the locks it needs in its initial request. Furthermore, each transaction needs to declare its read and write set (data items to be read/written during transaction), which is not always possible. Because of these limitations, C2PL is not used very frequently.

Soft currency

Soft currency indicates a type of currency whose value may depreciate rapidly or that is difficult to convert into other currencies. It is generally less desirable than hard currency to users. Soft currency can be in the form of paper, electronic or debt-based “IOUs” which have in the past been used in place of hard currency.

As “bad money” generally displaces “good money” (good money being used as a store of wealth and bad money being used as a means of exchange), it is generally the case that governments, private banks and other issuers of money have replaced hard currency with soft where the opportunity to do so has been permitted by the populace.


See also

  • Fiat currency
  • Private currency
  • Monetary reform
  • Debt-free money
  • Hard currency

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Frequency sharing

In telecommunication, frequency sharing is the assignment to or use of the same radio frequency by two or more stations that are separated geographically or that use the frequency at different times.

Frequency sharing reduces the potential for mutual interference where the assignment of different frequencies to each user is not practical or possible.

In a communications net, frequency sharing does not pertain to stations that use the same frequency.


References

  • Federal Standard 1037C

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Conservative two-phase locking

In computer science, conservative two-phase locking (C2PL) is a locking method used in DBMS and relational databases.

Conservative 2PL prevents deadlocks.

The difference between 2PL and C2PL is that C2PL’s transactions obtain all the locks they need before the transactions begin. This is to ensure that a transaction that already holds some locks will not block waiting for other locks.

In heavy lock contention, C2PL reduces the time locks are held on average, relative to 2PL and Strict 2PL, because transactions that hold locks are never blocked.

In light lock contention, C2PL holds more locks than is necessary, because it is hard to tell what locks will be needed in the future, thus leads to higher overhead.

Also, a transaction will not even obtain any locks if it cannot obtain all the locks it needs in its initial request. Furthermore, each transaction needs to declare its read and write set (data items to be read/written during transaction), which is not always possible. Because of these limitations, C2PL is not used very frequently.

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Lever tumbler lock

A lever tumbler lock is a type of lock that uses a set of levers to prevent the bolt from moving in the lock. In the simplest of these, lifting the tumbler above a certain height will allow the bolt to slide past.

‘Double acting’ Lever tumbler locks were invented in 1778 by Robert Barron of England. These required the lever to be lifted to a certain height by having a slot cut in the lever. So lifting the lever too far was as bad as not lifting the lever far enough. This is the type of lever lock most currently used today.

Lever locks generally use a bitted key. Some use a double-bitted key.


See also

  • Chubb detector lock

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Castellated nut

A castellated nut (also called a castle nut or a slotted nut) is a nut with slots (notches) cut into one end. The name comes from the nut’s resemblance to the crenellated parapet of a medieval castle. The bolt has a single hole drilled through its threaded end. The nut is tightened on the bolt so that the slots are aligned with the hole. The nut is then secured with a cotter pin or with locking wire. Castellated nuts are used in low-torque applications, such as holding a wheel bearing in place.


Fastener materials

Nuts and bolts are used to two surfaces together. This involves tightening and locking the nut. In applications subject to vibration, it is important to reduce the chance of failure by torquing the nut to a tension that exceeds the expected maximum load on the bolt. As the load changes, the clamping force exerted by the bolt changes, but the tension on the bolt stays the same.<ref>see Bolted joint</ref> Additional protection against failure is provided by various locking devices.

The most common bolt materials are carbon steel, stainless steel and alloy steels. The tensile strength<ref>Tensile strength refers to the force (stress) required to break a fastener apart. Tensile strength is measured in units of pressure (newtons per square meter in the metric (SI) system; pounds-force per square inch in the U.S. customary system). The conversion factor is 1 psi = 6894.757 Pa, or 1 ksi ≈ 6.89 Mpa. In engineering practice, “ksi” are called “kips.”</ref> of carbon steel is typically 375 Mpa (55 ksi); stainless steel 1,400 Mpa (200 ksi); heat treated and alloy steels up to 2,000 Mpa (300 ksi). The strength of a nut/bolt combination depends primarily on the strength of the bolt. The first six threads of the nut take up essentially the whole load.<ref>Johns WE, Notes on Nuts and Bolts, p. 1. http://www.gizmology.net/nutsbolts.htm</ref>


Locking devices


Split-beam locknuts

Split-beam locknuts have slots cut into the top. They bear a superficial resemblance to castellated nuts. In split-beam nuts, however, the slotted areas are pressed together, reducing the thread diameter. When a bolt is threaded through the slotted area, the compressed segments are forced apart, producing friction forces that prevent subsequent movement of the nut.


Lockwires

Lockwires (safety wires) are used to connect nuts securely.<ref>FAA advisory circular AC 43.13-1B Chapter 7, “Safetying.” Builder’s Guide to Aircraft Materials, Rev.1 (January 15, 2006). http://www.auf.asn.au/scratchbuilder/safetying.html </ref> They are threaded through holes in the nut, twisted together, and connected to adjacent nuts. They are configured so that tension on the wire tightens the nut. Any tendency of a nut to loosen is counteracted by the tightening force it exerts on adjacent nuts. Lockwiring is used in aerospace and other critical applications. Castellated nuts can be lockwired.


Jam nuts

Two nuts are tightened over the bolt and then torqued against each other. The smaller (jam) nut is tightened first. This puts stress on the bottom of the bolt threads (the side closest to the mating surface). The larger nut is then tightened against the jam nut. This puts stress on the top of the threads. At the junction of the two nuts, the thread is clamped by forces in opposite directions. The two nuts are locked to the bolt at this point.<ref>Calvert JB. The Jam Nut. http://www.du.edu/~jcalvert/tech/jamnut.htm</ref>


Lock washers

Helical washers are compressed (like a spring) when the nut is tightened. When fully compressed, however, they are functionally equivalent to a flat washer and provide no additional locking ability.<ref>Barrett, RT. Fastener Design Manual. NASA Reference Publication 1228, 1990, p.9. http://www.tcnj.edu/~rgraham/barrett/manual1-A.html</ref>

Toothed (star) washers have teeth that bite into the nut (or bolt head) and the mating surface.


Other locking devices

Serrated-face nuts (flange nuts) have serrations on the bottom that dig into the mating surface. Nylon lock nuts are manufactured with nylon inserts that apply friction forces to the bolt. Locking adhesives (e.g. Loctite) are epoxy adhesives that bond the nut and bolt together.


References

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Bibliography

Barrett, RT. Fastener Design Manual. NASA Reference Publication 1228, 1990. http://www.tcnj.edu/~rgraham/barrett/manual1-A.html

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Set (video game)

A set is a group of items with similar properties that, when combined, give an overall set bonus. Typically, these bonuses are added when there are two or more pieces of the set equipped, and each subsequent bonus stacks with the one before it.

For example, in World of Warcraft, the “Black Dragon Mail” [1] set gives:

  • Improves your chance to hit by 1% with two items
  • Improves your chance to get a critical strike by 2% with three items
  • +10 Fire Resistance with four items

Theforefore, if a player had all four pieces, they would receive the chance to hit, critical strike and fire resistance bonus.

Sets can range anywhere from 2 pieces to upwards of 8 or 10, depending on the game and the available equipment slots. Also, as well as improved bonuses, item sets usually have a distinct look to them, through use of unique game artwork.


External links

  • List of sets in Diablo II
  • List of sets in World of Warcraft

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Distributed transaction

A distributed transaction is an operations bundle, in which two or more network hosts are involved. Usually, hosts provide transactional resources, while the transaction manager is responsible for creating and managing a global transaction that encompasses all operations against such resources. Distributed transactions, as any other transactions, must have all four ACID properties, where atomicity guarantees all-or-nothing outcomes for the unit of work (operations bundle).

Open Group, a vendor consortium, proposed the X/Open Distributed Transaction Processing (DTP) Model, which became a de-facto standard for behavior of transaction model components.

Databases are common transactional resources and, often, transactions span a couple of such databases. In this case, a distributed transaction can be seen as a database transaction that must be synchronized (or provide ACID properties) among multiple participating databases which are distributed among different physical locations. The isolation property (the I of ACID) poses a special challenge for multi database transactions, since the (global) serializability property could be violated, even if each database provides it (see also global serializability). In practice most commercial database systems use strong strict two phase locking (SS2PL) for concurrency control, which ensures global serializability, if all the participating databases employ it. (see also commitment ordering for multidatabases.)

A common algorithm for ensuring correct completion of a distributed transaction is the two-phase commit. This algorithm is usually applied for updates able to commit in a short period of time, ranging from couple of milliseconds to couple of minutes.

There are also long-lived distributed transactions, for example a transaction to book a trip, which consists of booking a flight, a rental car and a hotel. Since booking the flight might take up to a day to get a confirmation, two-phase commit is not applicable here, it will lock the resources for this long. In this case more sophisticated techniques that involve multiple undo levels are used. The way you can undo the hotel booking by calling a desk and cancelling the reservation, a system can be designed to undo certain operations (unless they are irreversibly finished).

In practice, long-lived distributed transactions are implemented in systems based on Web Services. Usually these transactions utilize principles of Compensating Transactions, Optimism and Isolation Without Locking. X/Open standard does not cover long-lived DTP.

A couple of modern technologies, including Enterprise Java Beans (EJBs) and Microsoft Transaction Server (MTS) fully support distributed transaction standards.


References

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Payment gateway

A payment gateway is an e-commerce application service provider service that authorizes payments for e-businesses, online retailers, bricks and clicks, or traditional brick and mortar. It is the equivalent of a physical POS(Point-of-sale) terminal located in most retail outlets. Payment gateways encrypt sensitive information, such as credit card numbers, to ensure that information passes securely between the customer and the merchant.


How payment gateways work

A payment gateway facilitates the transfer of information between a payment portal (such as a website or IVR service) and the Front End Processor or acquiring bank; quickly and securely.

When a customer orders a product from a payment gateway enabled merchant, the payment gateway performs a variety of tasks to process the transaction; completely invisible to the customer. For example:

  • A customer places order on website by pressing the ‘Submit Order’ or equivalent button, or perhaps enters his/her card details using an automatic phone answering service.
  • If the order is via a website, the customer’s web browser encrypts the information to be sent between the browser and the merchant’s webserver. This is usually done via SSL (Secure Socket Layer) encryption.
  • The merchant then forwards the transaction details through to his/her payment gateway which holds the detail of the merchant account transaction. This is often another SSL encrypted connection to the payment server hosted by the payment gateway.
  • The payment gateway which receives the transaction information from the merchant forwards it to the merchant’s acquiring bank.
  • The acquiring bank then forwards the transaction information to the issuing bank (the bank that issued the credit card to the customer) for authorization.
  • The card issuing bank receives the authorization request and sends a response back to the payment gateway (via the acquiring bank) with a response code. In addition to determining the fate of the payment, (i.e approved or declined) the response code is used to define the reason why the transaction failed (such as insufficient funds, or bank link not available)
  • The payment gateway receives the response, and forwards it on to the website (or whatever interface was used to process the payment) where it is interpreted and a relevant response then relayed back to the cardholder.
  • The entire process typically takes 3-4 seconds
  • At the end of the bank-day (or settlement period) the acquiring bank deposits the total of the approved funds in to the merchant’s nominated account. This could be an account with the acquiring bank if the merchant does his/her banking with the same bank, or a scrape account with another bank.


External links

  • Six Payment Gateways Reviewed - Side-by-side comparison of six popular payment gateways

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Saint Georges, Delaware

Saint Georges, Delaware is an unincorporated town situated on the Chesapeake and Delaware Canal in New Castle County, Delaware, about midway between the Delaware River and Chesapeake Bay.

The Chesapeake & Delaware Canal Bridge (Delaware Route 1) passes just west of town. It is the only cable-stayed bridge in the Delaware Valley and one of the first in the nation. It opened in 1995 as a replacement to the still standing St. Georges Bridge, which carries U.S. Highway 13 over the town of Saint Georges and the Canal. The St. Georges Bridge is in turn a replacement for a former lift bridge that sat in the middle of town. That bridge was knocked down in November 1939 when the German freighter Waukegan lost power and hit the south tower of the bridge causing it to collapse. Two people died that evening, the bridge tender and a sailor that was on the bridge of the ship at the time of the accident. One other bridge spanned the C & D Canal before the lift bridge. It was a small pedestrian swing bridge that crossed over the former Saint Georges Locks. It was destroyed when the locks were dismantled during the first widening and deepening (to sea level) of the canal.

Its ZIP Code is 19733.

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Pleasures Pave Sewers

Pleasures Pave Sewers is the debut album of grindcore band Lock Up, a side project of Napalm Death, featuring Peter Tägtgren on vocals.


Track listing

  1. “After Life in Purgatory” (2:08)
  2. “Submission” (2:46)
  3. “Triple Six Suck Angels” (2:58)
  4. “Delirium” (1:56)
  5. “Pretenders of the Throne” (1:45)
  6. “Slow Bleed Gorgon / Pleasures Pave Sewers” (3:36)
  7. “Ego Pawn” (1:53)
  8. “The Dreams Are Sacrificed” (2:06)
  9. “Tragic Faith” (2:30)
  10. “Darkness of Ignorance” (2:23)
  11. “Salvation thru’ Destruction” (2:24)
  12. “Leech Eclipse” (0:56)
  13. “Fever Landscapes” (1:47)


Credits

  • Peter Tägtgren - Vocals
  • Nicholas Barker - Drums
  • Shane Embury - Bass
  • Jesse Pintado - Guitars

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Lock and Dam No. 2

The first lock and dam to be built on the Mississippi was also called Lock and Dam No. 2. See Meeker Island Lock and Dam.

Lock and Dam No. 2 is located along the Upper Mississippi River near Hastings, Minnesota and was originally built in 1930. The eastern dam portion is 722 feet (220 m) wide and has 19 tainter gates. A hydroelectric station that produces about 4.4 megawatts is owned by the city of Hastings, while the 110 × 600 foot (34 × 183 m) lock is operated by the St. Paul district of the U.S. Army Corps of Engineers’ Mississippi Valley Division. There’s also a wide earthen dam on the western side of the facility.

Following construction, the original lock walls settled and began to lean out of alignment, so a replacement lock was built. It was finished in 1948. A rehabilitation phase ran from 1987 to 1995.


External links

  • USACE St. Paul District: Lock and Dam No. 2
  • Google Maps: Lock and Dam No. 2
  • USGS, Locks 1 through 13

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Elbląg Canal

Elbląg Canal (, ) is a canal in Poland, in Warmian-Masurian Voivodeship, 80.5 km in length, which runs southward from Lake Druzno (connected by the river Elbląg to the Vistula Lagoon), to the river Drwęca and lake Jeziorak. It can accommodate small vessels up to 50 tons displacement. The difference in water levels approaches 100 m, and is overcome using locks and a remarkable system of tracks between lakes.

Today it is used mainly for recreational purposes. It is considered one of the most significant monuments related to the history of technology on the territory of modern Poland.


History

The canal was designed in 1825-1844 by Georg Steenke, carrying out the commission given by the king of Prussia. Construction began in 1844. As the route was not important enough to justify building expensive, traditional locks between lakes, an ingenious system of tracks was employed instead, though the canal includes a few locks as well. Built originally under the name Oberländischer Kanal (Overland Canal) and situated in the Kingdom of Prussia, it was opened in 1860. Since 1945 the canal has been located in Poland. After wartime damage was repaired, it was restored to operation in 1948 and is now used for tourism.


External links

  • Official webpage
  • Photo gallery of the canal
  • Warsaw Voice article

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Transaction

A transaction is an agreement, communication, or movement carried out between separate entities or objects, often involving the exchange of items of value, such as information, goods, services and money.

  • Financial transaction
  • Database transaction
  • Atomic transaction
  • Transaction processing
  • POS Transaction

Transaction may also refer to:

  • “Transaction,” an episode of the Death Note anime series, see List of Death Note episodes