Tsa locks for luggage Articles

In computer science, multiple granularity locking (MGL), sometimes called the John Rayner locking method, is a locking method used in database management systems (DBMS) and relational databases.

In MGL, locks are set on objects that contain other objects. MGL exploits the hierarchical nature of the contains relationship. For example, a database may have files, which contain pages, which further contain records. This can be thought of as a tree of objects, where each node contains its children. A lock locks a node and its descendants.

Multiple granularity locking is usually used with Non-strict two-phase locking to guarantee serializability. MGL uses lock escalation to determine granularity lock on a node and its ancestors.

Lock Modes

In addition to shared (S) locks and exclusive (X) locks from other locking schemes, like Strict two-phase locking, MGL also uses intention shared and intention exclusive locks. IS locks conflict with X locks, while IX locks conflict with S and X locks. The null lock (NL) is compatible with everything.

To lock a node in S (or X), MGL has the transaction locks all of its ancestors with IS (or IX), so if a transaction locks a node in S (or X), no other transaction can access its ancestors in X (or S and X).

MGL locking modes are compatible with each other as defined in the following matrix.

The McAlpine Locks and Dam refers to the series of locks and the hydroelectric dam in Louisville, Kentucky at the Falls of the Ohio. They are located at mile point 606.8 and control a 72.9 mile (117 km) long navigation pool. This was the first major engineering project on the Ohio River, and the first official name of the system of canal locks was the Louisville and Portland Canal, which was completed in 1830 to allow shipping traffic to navigate through the Falls of the Ohio. From 1925 to 1927, a dam for generating hydroelectric power was added, and the system of canals was expanded, first by a private company and then by the U.S. Army Corps of Engineers. The hydroelectric plant at the time was the seventh largest hydroelectric plant in the United States.

The system was renamed the McAlpine Locks and Dam in 1960 in honor of William McAlpine, who was the only civilian to have ever served as district engineer for the Corps of Louisville. At present, the normal pool elevation is 420 feet (130 m) above sea level and the drainage area above the dam is 91,170 square miles (236,000 km²). The average daily flow at McAlpine is 118,000 cubic feet per second (3,340 m³/s). The lock chambers are located at the dam on the Kentucky side of the Ohio River and are capable of a normal lift of 37 feet (11 m) between the McAlpine pool upstream and the Cannelton pool downstream. The hydroelectric plant consists of eight turbine units with a net power generation capacity of 80,000 kilowatts. The hydroelectric plant is currently undergoing an 8-year long rehabilitation project. This will extend the life of the 1920s era turbine-generator units and increase power output to 100 megawatts.

In October 2003, McAlpine was designated a Historic Civil Engineering Landmark by the American Society of Civil Engineers.

The McAlpine locks are currently undergoing a 10-year, $278 million expansion project scheduled to be completed in 2008.

The hydroelectric plant is owned and operated by LG&E, a subsidiary of E.ON U.S., while the locks are operated by the Army Corps of Engineers.

A solenoid bolt is a type of electronic-mechanical locking mechanism. This type of lock is characterized by the use of a solenoid to throw the bolt. Sophisticated solenoid bolt locks may use microprocessors to perform voltage regulation, reduce power consumption, and/or provide access control. Depending on the strength of the solenoid, some models can provide a holding force on the order of 1000 kg. A solenoid bolt can be designed either to fail open (the lock opens on power loss) or to fail closed (the device is locked upon power loss); cf fail safe. Some models may be suitable for high-security sites.

A bahut is a portable coffer or chest, with a rounded lid covered in leather, garnished with nails, once used for the transport of clothes or other personal luggage, it was, in short, the original portmanteau. This ancient receptacle, of which mention is made as early as the 14th century — its traditional form is still preserved in many varieties of the travelling trunk — sometimes had its leather covering richly ornamented, and occasionally its interior was divided into compartments; but whatever the details of its construction it was always readily portable. Towards the end of the 17th century the name fell into disuse, and was replaced by coffer, which probably accounts for its misuse by the French romantic writers of the early 19th century. They applied it to almost any antique sideboard, cupboard or wardrobe, and its use became hopelessly confused.

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.

In Databases and Transaction processing, Two phase locking, (2PL) is a concurrency control locking protocol, mechanism, that guarantees Serializability. It is also the name of a class (set) of transaction schedules. Using locks that block processes, 2PL is subject to deadlocks that result from the mutual blocking of two transactions or more.

Two phase locking

According to the Two phase locking protocol, locks are handled by a transaction in two distinct, consecutive phases during the transaction’s execution:

Phase 1: Locks are acquired and no locks are released.

Phase 2: Locks are released and no locks are acquired.

The serializability property is guaranteed for a schedule with transactions that obey the protocol. The 2PL schedule class is defined as the class of all the schedules comprising transactions with data access orders that could be generated by the 2PL protocol.

Strict two phase locking

The Strict two phase locking (S2PL) class of schedules is the intersection of the 2PL class with the class of schedules possessing the Strictness property.

To comply with the S2PL protocol a transaction needs to comply with 2PL, and release its write (exclusive) locks only after it has ended, i.e., being either committed or aborted.

S2PL is a special case of 2PL, i.e., the S2PL class is a proper subclass of 2PL.

Strong strict two phase locking

To comply with the Strong strict two phase locking (SS2PL) protocol a transaction needs to comply with 2PL, and release both its write (exclusive) and read (shared) locks only after it has ended, i.e., being either committed or aborted.
A transaction obeying SS2PL can be viewed as having Phase 1 that lasts its entire execution duration, and no Phase 2 (or degenerate Phase 2). Thus, only one phase is actually left, and “two-phase” in the name seems to be still utilized due to the historical development of the concept from 2PL. The SS2PL property of a schedule is also called Rigorousness, and an SS2PL schedule is also called a Rigorous schedule.

SS2PL is a special case of S2PL, i.e., the SS2PL class of schedules is a proper subclass of S2PL (every SS2PL schedule is also an S2PL schedule, but S2PL schedules exist that are not SS2PL).

SS2PL is the concurrency control protocol of choice for most database systems since it provides besides serializability also Strictness, which is instrumental for efficient database recovery, and also Commitment ordering (CO) for participating in environments where a CO based Global serializability solution is employed.

Fobney Lock is a lock on the River Kennet in the Small Mead area of Reading in the English county of Berkshire.

Fobney Lock was built between 1718 and 1723 under the supervision of the engineer John Hore of Newbury, and this stretch of the river is now administered by British Waterways and known as the Kennet Navigation. It has a rise/fall of 7 ft 8 in (2.24 m).

There have been ongoing plans to turn Fobney Island, adjacent to the lock, into a wetlands nature reserve.

Bingley Three Rise Locks is a staircase of three locks on the Leeds and Liverpool Canal at Bingley. It opened in 1774 and was a major feat of engineering at the time along with the larger Five Rise (more details on construction and history here) opened at the same time just a few hundred meters further up. The lock comprises a ’staircase’ flight - the lower gate of one lock forms the upper gate of the next lock.

Southcote Lock is a lock on the River Kennet at Southcote within the town of Reading in Berkshire, England.

Southcote Lock was built between 1718 and 1723 under the supervision of the engineer John Hore of Newbury, and this stretch of the river is now administered by British Waterways and known as the Kennet Navigation. It has a rise/fall of 5 ft 3 in (1.65 m).

The Victorian brick building that overseas Southcote Lock is the redundant Southcote Pumping Station which, when it opened in 1850, was the key to Reading’s demanding water needs.

The Great Lakes Waterway is a system of channels and canals that makes all of the Great Lakes accessible to oceangoing vessels. Its principal civil engineering components are the Welland Canal, bypassing Niagara Falls between Lake Ontario and Lake Erie, and the Soo Locks, bypassing the rapids of the St. Marys River between Lake Superior and Lake Huron, at Sault Sainte Marie. Maintained channels serve the St. Clair River and Detroit River between Lake Huron and Lake Erie. A United States Coast Guard icebreaker helps keep the passage open for much of the winter, although shipping usually ceases for 2 or 3 months each year.

The Great Lakes Waterway is supplemented by the Saint Lawrence Seaway, which makes the Saint Lawrence River navigable from Montreal to Kingston, Ontario. The two waterways are often jointly referred to as the St. Lawrence Seaway. The Great Lakes Seaway has larger locks and deeper drafts than the St. Lawrence Seaway with the result that a number of lake freighters are confined to the lakes, being small enough to operate on the Waterway but too large to pass down the Seaway.

The Great Lakes Waterway is co-administered by Canada and the United States.