Entries Tagged as 'and'

Declaration and forfeiture

In the sport of cricket a declaration occurs when a captain declares his team’s innings closed and a forfeiture is when a captain chooses to forfeit an innings. Declaration and forfeiture is covered in Law 14 of the Laws of cricket.


Declaration

The captain of the batting side may declare an innings closed, when the ball is dead, at any time during a match. Usually this is because the captain thinks his team has already scored enough runs to win the match, though tactical declarations are sometimes used in other circumstances.

A captain considering declaration must balance the risks of declaring too early (thus setting too low a target for the opposing team) against those of declaring too late or not at all (thus causing a draw by leaving insufficient time to complete the match).

The first captain to declare was Charles Wright in 1890. In a game against Kent at the Bat and Ball Ground in Gravesend, Wright declared Nottinghamshire’s second innings closed on 157 for 5 to set Kent a target of 231 to win. However, the tactic did not come off as the game was drawn with Kent on 98 for 9 and Nottinghamshire requiring one more wicket to win.


Forfeiture

Under the current Laws, a captain may forfeit either of his side’s innings. A forfeited innings shall be considered as a completed innings. Usually this happens in shorter competitive two-innings matches, where captains need to agree with each other how to set up the match so that there is a reasonable chance of a result. Winning a game gains a team considerably more points than drawing it, so captains are often willing to risk giving the opposition an opportunity to win that they otherwise would not have had as long as they are getting a similar opportunity in return.

Only one innings has been forfeited in Test match cricket. This was on 18 January 2000 at Centurion, South Africa in the fifth and final Test in a series between South Africa and England, which South Africa had already won as they were 2-0 up after the first four matches. After South Africa scored 155 for 6 on the first day, rain washed out the next three days. With only one day remaining, the match was set for a certain draw.

That was until Hansie Cronje, the South African captain, entered into a deal with his English counterpart, Nasser Hussain, that South Africa would continue batting till they reached about 250 and then declare. England and then South Africa would then both forfeit an innings, leaving England approximately 250 to win (in the event the target was 249). At that time, the laws did not permit a side batting first to forfeit an innings, so England’s first innings was treated as having been declared at 0 for 0 after 0 balls. England went on to score 251 for 8 and win by 2 wickets. Many of the South African team criticized Cronje at the time for setting too low a target.

It later emerged that Cronje had been approached by a bookmaker, and asked to ensure the game would end with a positive result. Nasser Hussain and the England team were not aware of this at the time, taking the request from the South African at face value.

On August 20, 2006, a test match involving Pakistan and England was forfeited by Pakistan after umpires declared a forfeit of the match by Pakistan due to a refusal to take the field after tea. This was caused by England being awarded five penalty runs after Pakistan were found to have tampered with the ball by the umpires. This was the first time a test match (and subsequently a test series) has been declared a forfeit.


References

  • Law 14 of the Laws of Cricket


External links

  • Scorecard of the game in which Wright became the first captain to declare an innings closed
  • Cricinfo page on Charles Wright
  • Scorecard of 2000 RSA vs ENG Centurion Match in which Cronje & Hussein forfeited innings

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Richmond Lock and Footbridge

Richmond Lock and Footbridge is a lock and pedestrian bridge, situated on the River Thames in south west London, England. It is the furthest downstream of all the Thames locks and is the only one owned and operated by the Port of London Authority. It was opened in 1894 and is situated close to the centre of Richmond in the south western suburbs of London. It connects Richmond on the east bank with the neighbouring district of St. Margarets on the west bank during the day, but is now closed at night to pedestrians - after 19:30 GMT or after 21:30 when BST is in use.


Description

Technically, Richmond Lock is a half-tide lock and barrage, which also incorporates a public footbrige. The footbridge crosses both the conventional lock and the barrage, which comprises three vertical steel sluice gates suspended from the footbridge structure. These gates weigh 32 tons each and are 66 feet in width and 12 foot in depth. The lock permits passage of vessels up to 250 feet long by 26 feet 8 inches wide.

For about two hours each side of high tide, the sluice gates which make up the barrage are raised into the footbridge structure above, and river traffic can pass through the barrage unimpeded. For the rest of the tidal cycle the sluice gates are closed, and ships and boats must use the lock alongside the barrage. The barrage has the effect of maintaining the water level between Richmond Lock and Teddington Lock (the next lock upstream) at or above half-tide level. The maximum fall of the lock is 10 feet.


See also

  • Locks on the River Thames
  • Crossings of the River Thames


External links

  • Richmond Lock (Tour UK)


Location

  • Wikimapia


Sources

  • http://www.thames-tideway.co.uk/richlock.shtm
  • http://www.victorianlondon.org/ql/queenslondon105.htm

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Jamie Whitten Lock and Dam

The Jamie Whitten Lock and Dam (formerly named Bay Springs Lock and Dam) is part of the Tennessee-Tombigbee Waterway.

Jamie Whitten Lock and Dam is located at in south Tishomingo County, Mississippi, close to the Prentiss County line.


References


External links

  • Tennessee-Tombigbee Waterway (U.S. Army Corps of Engineers)

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Sargent and Greenleaf

Sargent and Greenleaf, more commonly known among locksmithing circles as S&G, is a U.S. company that manufactures combination locks, key-operated safe and safe deposit box locks and associated equipment.

The company was established in 1865 when James Sargent and Halbert Greenleaf became partners. A manufacturing facility was built in Rochester, New York, and the company remained in that city until 1975. Since then, the company has been in Nicholasville, Kentucky.

In 1857 Sargent had designed the Sargent’s Magnetic Bank Lock, said to be the first successful key changeable combination lock.

In 1873 Sargent created the first time lock, using parts from eight-day clocks.

In 1880 Sargent connected one of his combination locks to a delay timer, creating the first time-delay combination lock.

Locks are sold around the world through associated distributors.

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Sargent and Greenleaf

Sargent and Greenleaf, more commonly known among locksmithing circles as S&G, is a U.S. company that manufactures combination locks, key-operated safe and safe deposit box locks and associated equipment.

The company was established in 1865 when James Sargent and Halbert Greenleaf became partners. A manufacturing facility was built in Rochester, New York, and the company remained in that city until 1975. Since then, the company has been in Nicholasville, Kentucky.

In 1857 Sargent had designed the Sargent’s Magnetic Bank Lock, said to be the first successful key changeable combination lock.

In 1873 Sargent created the first time lock, using parts from eight-day clocks.

In 1880 Sargent connected one of his combination locks to a delay timer, creating the first time-delay combination lock.

Locks are sold around the world through associated distributors.

Sargent and Greenleaf

Sargent and Greenleaf, more commonly known among locksmithing circles as S&G, is a U.S. company that manufactures combination locks, key-operated safe and safe deposit box locks and associated equipment.

The company was established in 1865 when James Sargent and Halbert Greenleaf became partners. A manufacturing facility was built in Rochester, New York, and the company remained in that city until 1975. Since then, the company has been in Nicholasville, Kentucky.

In 1857 Sargent had designed the Sargent’s Magnetic Bank Lock, said to be the first successful key changeable combination lock.

In 1873 Sargent created the first time lock, using parts from eight-day clocks.

In 1880 Sargent connected one of his combination locks to a delay timer, creating the first time-delay combination lock.

Locks are sold around the world through associated distributors.

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Test and Test-and-set

In computer science, the test-and-set CPU instruction is used to implement
mutual exclusion in multiprocessor environments. Although a correct lock can be implemented with test-and-set, it can lead to memory contention in busy lock (caused by bus locking and cache invalidation when test-and-set operation needs to access memory atomically).

To lower the overhead a more elaborate locking protocol test and test-and-set
is used. The main idea is not to spin in test-and-set but increase the likelihood of successful test-and-set by using following entry protocol to the lock: 

boolean locked := false // shared lock variable
procedure EnterCritical() {
  do {
    while (locked == true) skip // spin until lock seems free
  } while TestAndSet(locked) // actual atomic locking
}

Exit protocol is: 

procedure ExitCritical() {
  locked := false
}

The entry protocol uses normal memory reads to spin, waiting for the lock to become free. Test-and-set is only used to try to get the lock when normal memory read says its free. Thus the expensive atomic memory operations happens less often than in simple spin around test-and-set.

If the programming language used supports minimal evaluation, the entry protocol could be implemented as: 

 procedure EnterCritical() {
   while ( locked == true or TestAndSet(locked) == true )
     skip // spin until locked
 }


Caveat

Although this optimization is useful in system programming it should be avoided in high level concurrent programming. One example of bad usage of this idiom is double-checked locking, which is listed as an anti-pattern.


See also

  • Parallel processor
  • Parallel programming
  • Mutual exclusion
  • Test-and-set


References

  • Gregory R. Andrews, Foundations of Multithreaded, Parallel, and Distributed Programming, pp. 100-101. Addison-Wesley, 2000. ISBN 0-201-35752-6.

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Sargent and Greenleaf

Sargent and Greenleaf, more commonly known among locksmithing circles as S&G, is a U.S. company that manufactures combination locks, key-operated safe and safe deposit box locks and associated equipment.

The company was established in 1865 when James Sargent and Halbert Greenleaf became partners. A manufacturing facility was built in Rochester, New York, and the company remained in that city until 1975. Since then, the company has been in Nicholasville, Kentucky.

In 1857 Sargent had designed the Sargent’s Magnetic Bank Lock, said to be the first successful key changeable combination lock.

In 1873 Sargent created the first time lock, using parts from eight-day clocks.

In 1880 Sargent connected one of his combination locks to a delay timer, creating the first time-delay combination lock.

Locks are sold around the world through associated distributors.

Tags: Uncategorized by admin
No Comments »

Sargent and Greenleaf

Sargent and Greenleaf, more commonly known among locksmithing circles as S&G, is a U.S. company that manufactures combination locks, key-operated safe and safe deposit box locks and associated equipment.

The company was established in 1865 when James Sargent and Halbert Greenleaf became partners. A manufacturing facility was built in Rochester, New York, and the company remained in that city until 1975. Since then, the company has been in Nicholasville, Kentucky.

In 1857 Sargent had designed the Sargent’s Magnetic Bank Lock, said to be the first successful key changeable combination lock.

In 1873 Sargent created the first time lock, using parts from eight-day clocks.

In 1880 Sargent connected one of his combination locks to a delay timer, creating the first time-delay combination lock.

Locks are sold around the world through associated distributors.

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No Comments »