London and North Eastern Railway locomotive number 4468, 22 and 60022, named Mallard is a Class A4 4-6-2 Pacific steam locomotive built at Doncaster Works, England in 1938. It is significant as the holder of the world speed record for steam locomotives at 126 mph; the A4 class was designed by Nigel Gresley to power high-speed streamlined trains. The wind-tunnel-tested, aerodynamic body and high power allowed the class to reach speeds of over 100 miles per hour, although in everyday service it attained this speed. While in British Railways days regular steam-hauled rail services in the UK were limited to a 90 mph'line speed', pre-war, the A4s had to run above 90 mph just to keep schedule on trains such as the Silver Jubilee and The Coronation, with the engines reaching 100 mph on many occasions. Mallard covered one and a half million miles before it was retired in 1963; the locomotive weighs 165 tons, including the tender. It is painted LNER garter blue with red wheels and steel rims. Mallard is now part of the National Collection at the United Kingdom's National Railway Museum in York.
Mallard is the holder of the world speed record for steam locomotives at 126 mph. The record was achieved on 3 July 1938 on the slight downward grade of Stoke Bank south of Grantham on the East Coast Main Line, the highest speed was recorded at milepost 90¼, between Little Bytham and Essendine, it broke the 1936 German 002's record of 124.5 mph. The record attempt was carried out during the trials of a new quick-acting brake. Mallard was a good vehicle for such an endeavour; the A4 class was designed for sustained 100+ mph running, Mallard was one of a few of the class that were built with a double chimney and double Kylchap blastpipe, which made for improved draughting and better exhaust flow at speed. The A4's three-cylinder design made for stability at speed, the large 6 ft 8 in driving wheels meant that the maximum revolutions per minute was within the capabilities of the technology of the day. Mallard was four months old, meaning that it was sufficiently broken-in to run but not overly worn.
Selected to crew the locomotive on its record attempt were driver Joseph Duddington and fireman Thomas Bray. In the words of Rob Gwynne, assistant curator of rail vehicles at the National Railway Museum: Duddington aged 61, climbed into the cab, turned his cap around, drove Mallard into the history books, he had 27 years on the footplate, had once driven the Scarborough Flyer for 144 miles at over 74 mph, considered at the time to be the highest speed maintained by steam in the UK. The A4 class had had problems with the big end bearing for the middle cylinder, so the big end was fitted with a "stink bomb" of aniseed oil which would be released if the bearing overheated. Shortly after attaining the record speed, the middle big end did overheat and Mallard reduced speed, running at 70–75 miles an hour onwards to Peterborough, it travelled to Doncaster for repair. This had been foreseen by the publicity department, who had many pictures taken for the press, in case Mallard did not make it back to Kings Cross.
The Ivatt Atlantic that replaced Mallard at Peterborough was only just in sight when the head of publicity started handing out the pictures. Stoke Bank has a gradient of between 1:178 and 1:200. Mallard, pulling a dynamometer car and six coaches, topped Stoke Summit at 75 mph and accelerated downhill; the speeds at the end of each mile from the summit were recorded as: 87½, 96½, 104, 107, 111½, 116 and 119 mph. The speed recorded by instruments in the dynamometer car, marks were made every half second on a paper roll moving 24 inches for every mile travelled. Speeds could be calculated by measuring the distance between the timing marks. After the run staff in the dynamometer car calculated the speed over five second intervals, finding a maximum of 125 mph. 126 mph was seen for a single second but Gresley would not accept this as a reliable measurement and 125 miles an hour was the figure published. Ten years at the time of the 1948 Locomotive Exchanges, plaques were fixed to the sides of the locomotive, these stated 126 miles an hour, the speed accepted since.
Some writers have commented on the implausibility of the rapid changes in speed. A recent analysis has claimed that the paper roll in the dynamometer car was not moving at a constant rate and the peaks and troughs in the speed curve were just a result of this, the maximum speed being a sustained 124 mph for a mile. On arrival at King's Cross, driver Joe Duddington and inspector Sid Jenkins were quoted as saying that they thought a speed of 130 mph would have been possible if the train had not had to slow for the junctions at Essendine. In addition, at the time of the run there was a permanent way restriction to 15 mph just north of Grantham which slowed the train as they sought to build up maximum speed before reaching the high-speed downhill section just beyond Stoke tunnel. On 3 July 2013, Mallard celebrated 75 years since achieving the world speed record, to help commemorate this date all six surviving Class A4 locomotives were brought together around the turntable in
Data integrity is the maintenance of, the assurance of the accuracy and consistency of data over its entire life-cycle, is a critical aspect to the design and usage of any system which stores, processes, or retrieves data. The term is broad in scope and may have different meanings depending on the specific context – under the same general umbrella of computing, it is at times used as a proxy term for data quality, while data validation is a pre-requisite for data integrity. Data integrity is the opposite of data corruption; the overall intent of any data integrity technique is the same: ensure data is recorded as intended and upon retrieval, ensure the data is the same as it was when it was recorded. In short, data integrity aims to prevent unintentional changes to information. Data integrity is not to be confused with data security, the discipline of protecting data from unauthorized parties. Any unintended changes to data as the result of a storage, retrieval or processing operation, including malicious intent, unexpected hardware failure, human error, is failure of data integrity.
If the changes are the result of unauthorized access, it may be a failure of data security. Depending on the data involved this could manifest itself as benign as a single pixel in an image appearing a different color than was recorded, to the loss of vacation pictures or a business-critical database, to catastrophic loss of human life in a life-critical system. Physical integrity deals with challenges associated with storing and fetching the data itself. Challenges with physical integrity may include electromechanical faults, design flaws, material fatigue, power outages, natural disasters, acts of war and terrorism, other special environmental hazards such as ionizing radiation, extreme temperatures, pressures and g-forces. Ensuring physical integrity includes methods such as redundant hardware, an uninterruptible power supply, certain types of RAID arrays, radiation hardened chips, error-correcting memory, use of a clustered file system, using file systems that employ block level checksums such as ZFS, storage arrays that compute parity calculations such as exclusive or or use a cryptographic hash function and having a watchdog timer on critical subsystems.
Physical integrity makes extensive use of error detecting algorithms known as error-correcting codes. Human-induced data integrity errors are detected through the use of simpler checks and algorithms, such as the Damm algorithm or Luhn algorithm; these are used to maintain data integrity after manual transcription from one computer system to another by a human intermediary. Computer-induced transcription errors can be detected through hash functions. In production systems, these techniques are used together to ensure various degrees of data integrity. For example, a computer file system may be configured on a fault-tolerant RAID array, but might not provide block-level checksums to detect and prevent silent data corruption; as another example, a database management system might be compliant with the ACID properties, but the RAID controller or hard disk drive's internal write cache might not be. This type of integrity is concerned with the correctness or rationality of a piece of data, given a particular context.
This includes topics such as referential integrity and entity integrity in a relational database or ignoring impossible sensor data in robotic systems. These concerns involve ensuring. Challenges include software bugs, design flaws, human errors. Common methods of ensuring logical integrity include things such as check constraints, foreign key constraints, program assertions, other run-time sanity checks. Both physical and logical integrity share many common challenges such as human errors and design flaws, both must appropriately deal with concurrent requests to record and retrieve data, the latter of, a subject on its own. Data integrity contains guidelines for data retention, specifying or guaranteeing the length of time data can be retained in a particular database. To achieve data integrity, these rules are and applied to all data entering the system, any relaxation of enforcement could cause errors in the data. Implementing checks on the data as close as possible to the source of input, causes less erroneous data to enter the system.
Strict enforcement of data integrity rules results in lower error rates, time saved troubleshooting and tracing erroneous data and the errors it causes to algorithms. Data integrity includes rules defining the relations a piece of data can have, to other pieces of data, such as a Customer record being allowed to link to purchased Products, but not to unrelated data such as Corporate Assets. Data integrity includes checks and correction for invalid data, based on a fixed schema or a predefined set of rules. An example being textual data entered. Rules for data derivation are applicable, specifying how a data value is derived based on algorithm and conditions, it specifies the conditions on how the data value could be re-derived. Data integrity is enforced in a database system by a series of integrity constraints or rules. Three types of integrity constraints are an inherent part of the relational data model: entity integrity, referential integrity and domain integrity. Entity integrity concerns the concept of a primary key.
Entity integrity is an integrity rule which states that every table must have a primary key and that the column or c
The National Royalist Movement was a group within the Belgian Resistance in German-occupied Belgium during World War II. It was active chiefly in Brussels and Flanders and was the most politically right-wing of the major Belgian resistance groups; the MNR was founded in German-occupied Belgium soon after the Belgian defeat of May 1940 by former members of the far-right Catholic, authoritarian Rexist Party. As an organisation, it had a nationalist stance and was led by Eugène Mertens de Wilmars, a former admirer of the fascist, Leon Degrelle; the MNR wanted Belgium to become an authoritarian dictatorship under the rule of King Leopold III. In July 1941, the German occupation authorities became suspicious of the MNR and it was forced into hiding. After the arrest of Mertens de Wilmars in May 1942, it became overtly anti-German and began to engage in resistance activities; the MNR collected military intelligence. It provided help to Jews hiding from German persecution, Allied pilots shot down in occupied Europe and Belgian workers avoiding labour service in Germany.
In collaboration with the Secret Army and the Witte Brigade, the MNR participated in the capture of the Port of Antwerp shortly before the Allied liberation in September 1944. The operation prevented the Germans from destroying the installations and provided the Allies with access to their first intact deep-sea port. 160 members of the MNR were died in Nazi camps. Around 100 were killed in action during the liberation of the Port of Antwerp in September 1944. A monument to five members of the group killed during the liberation of Brussels is visible next to the Royal Museums of Fine Arts. Dujardin, Vincent. La Belgique sans Roi, 1940–1950. Nouvelle Histoire de Belgique. Brussels: Le Cri édition. ISBN 978-2-8710-6520-3. Van de Vijver, van Doorslaer and Verhoeyen, Etienne. België in de Tweede Wereldoorlog. Deel 6: Het verzet 2. DNB/Uitgeverij Peckmans, Kapellen. ISBN 9028913688. Pp. 91-94