National Physical Laboratory (United Kingdom) Explained

National Physical Laboratory
Type:Applied Physics
Research Field:Metrology
Head Label:Chief Executive Officer
Head:Peter Thompson
Staff:c. 1,000[1]
Address:Hampton Road, Teddington, TW11 0LW, England, UK
Coor:51.4264°N -0.3436°W
Operating Agency:NPL Management Ltd for the Department for Science, Innovation and Technology

The National Physical Laboratory (NPL) is the national measurement standards laboratory of the United Kingdom. It sets and maintains physical standards for British industry.

Founded in 1900, the NPL is one of the oldest metrology institutes in the world. Research and development work at the laboratory has contributed to the advancement of many disciplines of science, including the development of early computers in the late 1940s and 1950s, construction of the first accurate atomic clock in 1955, and the invention and first implementation of packet switching in the 1960s, which is today one of the fundamental technologies of the Internet.[2] [3] The former heads of NPL include many individuals who were pillars of the British scientific establishment.[4] [5]

NPL is based at Bushy Park in Teddington, west London. It is operated by NPL Management Ltd, a company owned by the Department for Science, Innovation and Technology, and is one of the most extensive government laboratories in the United Kingdom.

History

Precursors

In the 19th century, the Kew Observatory was run by self-funded devotees of science. In the early 1850s, the observatory began charging fees for testing meteorological instruments and other scientific equipment. As universities in the United Kingdom created and expanded physics departments, the governing committee of the observatory became increasingly dominated by paid university physicists in the last two decades of the nineteenth century. By this time, instrument-testing was the observatory's main role. Physicists sought the establishment of a state-funded scientific institution for testing electrical standards.[6]

Founding

The National Physical Laboratory was established in 1900 at Bushy House in Teddington. Its purpose was "for standardising and verifying instruments, for testing materials, and for the determination of physical constants".[7] The laboratory was run by the UK government, with members of staff being part of the civil service. It grew to fill a large selection of buildings on the Teddington site.[8]

Late 20th century

Administration of NPL was contracted out in 1995 under a Government Owned Contractor Operated (GOCO) model, via a new operating company, NPL Management Ltd. Serco won the bid and all staff transferred to their employment. Under this regime, overhead costs halved, third-party revenues grew by 16% per annum, and the number of peer-reviewed research papers published doubled.[9] [10]

NPL procured a large state-of-the-art laboratory under a Private Finance Initiative contract in 1998. The construction was undertaken by John Laing.[11]

21st century

The new laboratory building, which had been maintained by Serco, was transferred back to the DTI in 2004 after the private sector companies involved made losses of over £100m.

It was decided in 2012 to change the operating model for NPL from 2014 onwards to include academic partners and to establish a postgraduate teaching institute on site.[12] The date of the changeover was later postponed for a year.[13] The candidates for lead academic partner were the Universities of Edinburgh, Southampton, Strathclyde and Surrey[14] with an alliance of the Universities of Strathclyde and Surrey chosen as preferred partners.[15]

Funding was announced in January 2013 for a new £25m Advanced Metrology Laboratory that will be built on the footprint of an existing unused building.[16] [17]

NPL Management Ltd and the operation of the laboratory transferred back to the Department for Business, Innovation and Skills (now the Department for Science, Innovation and Technology) on 1 January 2015.[18]

Notable researchers

Researchers who have worked at NPL include:[19] D. W. Dye who did important work in developing the technology of quartz clocks; the inventor Sir Barnes Wallis who did early development work on the "Bouncing Bomb" used in the "Dam Busters" wartime raids;[20] H. J. Gough, one of the pioneers of research into metal fatigue, who worked at NPL for 19 years from 1914 to 1938; and Sydney Goldstein and Sir James Lighthill who worked in NPL's aerodynamics division during World War II researching boundary layer theory and supersonic aerodynamics respectively.[21]

Alan Turing, known for his work at the Government Code and Cypher School (GC&CS) at Bletchley Park during the Second World War to decipher German encrypted messages, worked at the National Physical Laboratory from 1945 to 1947.[22] He designed there the ACE (Automatic Computing Engine), which was one of the first designs for a stored-program computer. Clifford Hodge also worked there and was engaged in research on semiconductors. Others who have spent time at NPL include Robert Watson-Watt, generally considered the inventor of radar, Oswald Kubaschewski, the father of computational materials thermodynamics and the numerical analyst James Wilkinson.[23]

Metallurgist Walter Rosenhain appointed the NPL's first female scientific staff members in 1915, Marie Laura Violet Gayler and Isabel Hadfield.[24]

Research

NPL research has contributed to physical science, materials science, computing, and bioscience. Applications have been found in ship design, aircraft development, radar, computer networking, and global positioning.[25]

Atomic clocks

The first accurate atomic clock, a caesium standard based on a certain transition of the caesium-133 atom, was built by Louis Essen and Jack Parry in 1955 at NPL.[26] [27] Calibration of the caesium standard atomic clock was carried out by the use of the astronomical time scale ephemeris time (ET).[28] This led to the internationally agreed definition of the latest SI second being based on atomic time.[29]

Computing

Early computers

NPL has undertaken computer research since the mid-1940s.[30] From 1945, Alan Turing led the design of the Automatic Computing Engine (ACE) computer. The ACE project was overambitious and floundered, leading to Turing's departure.[31] Donald Davies took the project over and concentrated on delivering the less ambitious Pilot ACE computer, which first worked in May 1950. Among those who worked on the project was American computer pioneer Harry Huskey. A commercial spin-off, DEUCE was manufactured by English Electric Computers and became one of the best-selling machines of the 1950s.[31]

Packet switching

See main article: Packet switching and NPL network.

See also: History of the Internet. Beginning in the mid-1960s, Donald Davies invented and pioneered the implementation of packet switching, now the dominant basis for data communications in computer networks worldwide.[32] Davies designed and proposed a national commercial data network in his 1965 Proposal for the Development of a National Communications Service for On-line Data Processing. Subsequently, the NPL team, led by Roger Scantlebury, were the first to implement packet switching in the local-area NPL network in early 1969,[33] [34] [35] [36] which operated until 1986. They carried out work to analyse and simulate the performance of a wide-area packet-switched network capable of providing data communications facilities to most of the U.K.[37] Their research and practice influenced the ARPANET in the United States, the forerunner of the Internet, and other researchers in the UK and Europe, including Louis Pouzin.[38] [39] [40]

NPL sponsors a gallery, opened in 2009, about the development of packet switching and "Technology of the Internet" at The National Museum of Computing.[41]

Internetworking

NPL internetworking research was led by Davies, Barber and Scantlebury, who were members of the International Network Working Group (INWG).[42] [43] [44] [45] [46] Connecting heterogeneous computer networks creates a "basic dilemma" since a common host protocol would require restructuring the existing networks. NPL connected with the European Informatics Network (Barber directed the project and Scantlebury led the UK technical contribution)[47] [48] [49] by translating between two different host protocols; that is, using a gateway. Concurrently, the NPL connection to the Post Office Experimental Packet Switched Service used a common host protocol in both networks. NPL research confirmed establishing a common host protocol would be more reliable and efficient.[50] The EIN protocol helped to launch the proposed INWG standard.[51] Bob Kahn and Vint Cerf acknowledged Davies and Scantlebury in their 1974 paper "A Protocol for Packet Network Intercommunication".[52]

Scrapbook

Scrapbook was an information storage and retrieval system that went live in mid-1971. It included what would now be called word processing, e-mail and hypertext, anticipating many elements of the World Wide Web. The project was managed by David Yates who said of it "We had a community of bright people that were interested in new things, they were good fodder for a system like Scrapbook" and "When we had more than one Scrapbook system, hyperlinks could go across the network without the user knowing what was happening".[53] [54] It was decided that any commercial development of Scrapbook should be left to industry and it was licensed to Triad and then to BT who marketed it as Milepost and developed a transaction processor as an additional feature. Various implementations were marketed on DEC, IBM and ITL machines. All NPL implementations of Scrapbook were closed down in 1984.[55]

Secure communication

In the early 1990s, the NPL developed three formal specifications of the MAA: one in Z,[56] one in LOTOS,[57] and one in VDM.[58] [59] The VDM specification became part of the 1992 revision of the International Standard 8731–2, and three implementations in C, Miranda, and Modula-2.[60]

Electromagnetics

A 2020 study by researchers from Queen Mary University of London and NPL successfully used microwaves to measure blood-based molecules known to be influenced by dehydration.

Metrology

The National Physical Laboratory is involved with new developments in metrology, such as researching metrology for, and standardising, nanotechnology.[61] It is mainly based at the Teddington site, but also has a site in Huddersfield for dimensional metrology[62] and an underwater acoustics facility at Wraysbury Reservoir near Heathrow Airport.[63]

Directors of NPL

Directors of NPL include a number of notable individuals:[64]

Managing Directors

Chief Executive Officers

See also

Further reading

External links

Notes and References

  1. Web site: About us. 2021-02-24. NPLWebsite. en. 23 July 2020. https://web.archive.org/web/20200723020908/https://www.npl.co.uk/about-us/. live.
  2. Needham. Roger M.. 2002. Donald Watts Davies, C.B.E. 7 June 1924 – 28 May 2000. Biographical Memoirs of Fellows of the Royal Society. en. 48. 87–96. 10.1098/rsbm.2002.0006. 72835589. 0080-4606. This was the start of 10 years of pioneering work at the NPL in packet switching. ... At that lecture he first became aware that Paul Baran, of the RAND Corporation, had proposed a similar system in the context of military communication. His report was not as detailed as Davies’s design and had not been acted on..
  3. News: Feder. Barnaby J.. Donald W. Davies, 75, Dies; Helped Refine Data Networks. 2000-06-04. The New York Times. 2020-01-10. en-US. 0362-4331. Donald W. Davies, who proposed a method for transmitting data that made the Internet possible. 6 April 2019. https://web.archive.org/web/20190406213400/https://www.nytimes.com/2000/06/04/business/donald-w-davies-75-dies-helped-refine-data-networks.html. live.
  4. Book: Naughton, John . A Brief History of the Future . 2015-09-24 . Orion . 978-1-4746-0277-8 . en . 4 June 2020 . https://web.archive.org/web/20200818231620/https://books.google.com/books?id=bbonCgAAQBAJ&q=English+outfit . 18 August 2020 . live.
  5. Book: Russell, Andrew L. . Open Standards and the Digital Age: History, Ideology, and Networks . 2014-04-28 . Cambridge University Press . 978-1-139-91661-5 . en . 27 October 2020 . https://web.archive.org/web/20211010001412/https://books.google.com/books?id=OVpzAwAAQBAJ&q=NPL . 10 October 2021 . live.
  6. Macdonald. Lee T.. 2018-11-26. University physicists and the origins of the National Physical Laboratory, 1830–1900. History of Science. 59. 1. 73–92. en. 10.1177/0073275318811445. 30474405. 53792127. 25 February 2021. 16 November 2020. https://web.archive.org/web/20201116091341/https://journals.sagepub.com/doi/10.1177/0073275318811445. live.
  7. Web site: history. live. 6 May 2018. National Physical Laboratory. 26 June 2019. https://web.archive.org/web/20190626211736/https://www.npl.co.uk/history.
  8. Web site: 2013. Development of the NPL Site 1900-1970.pdf. dead. https://web.archive.org/web/20131224082931/http://www.npl.co.uk/upload/pdf/Development%20of%20the%20NPL%20Site%201900-1970.pdf. 24 December 2013. 23 December 2013.
  9. http://www.ethosjournal.com/home/item/301-labs-under-the-microscope Labs under the microscope – Ethos
  10. Book: Committee . Great Britain: Parliament: House of Commons: Science and Technology . Identity Card Technologies: Scientific Advice, Risk and Evidence; Sixth Report of Session 2005-06; Report, Together with Formal Minutes, Oral and Written Evidence . Technology . Great Britain Parliament House of Commons Select Committee on Science and . 2006-08-04 . The Stationery Office . 978-0-215-03047-4 . en.
  11. Web site: 2013. The Termination of the PFI Contract for the National Physical Laboratory |National Audit Office. 23 December 2013. nao.org.uk. 24 December 2013. https://web.archive.org/web/20131224111648/https://www.nao.org.uk/report/the-termination-of-the-pfi-contract-for-the-national-physical-laboratory/. live.
  12. Web site: Microsoft Word - Briefing document 26 March 2013_final - establishing-a-new-partnership-for-the-npl-briefing-note.pdf . 2013 . 23 December 2013 . 24 December 2013 . https://web.archive.org/web/20131224104610/http://www.bis.gov.uk/assets/nmo/docs/nms/future-operation-of-npl/establishing-a-new-partnership-for-the-npl-briefing-note.pdf . live .
  13. Web site: Escape. The. Serco. 2021-02-24. Serco. en. 24 January 2021. https://web.archive.org/web/20210124091023/https://www.serco.com/uk/media-and-news/2014/national-physical-laboratory-contract-extension. live.
  14. Web site: Future operation of the National Physical Laboratory | National Measurement System | BIS . bis.gov.uk . 2013 . 23 December 2013 . 24 December 2013 . https://web.archive.org/web/20131224112316/http://www.bis.gov.uk/nmo/national-measurement-system/future-operation-of-npl . live .
  15. Web site: Press Release – Universities of Surrey and Strathclyde selected as strategic partners in the future operation of the National Physical Laboratory . NPL . 10 July 2014 . 11 July 2014 . 5 . 14 July 2014 . https://web.archive.org/web/20140714153235/http://www.npl.co.uk/upload/pdf/20140710-npl-future-op-press-release.pdf . live .
  16. Announcement of £25 million Advanced Metrology Laboratory at NPL . David . Willetts . bis.gov.uk . 2013 . 23 December 2013 . 24 December 2013 . https://web.archive.org/web/20131224092810/http://www.bis.gov.uk/nmo/news-and-events/news/2013/Jan/Announcement-of-advanced-metrology-laboratory . live .
  17. Web site: National Physical Laboratory, Hampton Road, Teddington, Middlesex, United Kingdom, TW11 0LW - aml-letter-july2013.pdf . 2013 . 23 December 2013 . https://web.archive.org/web/20131224083033/http://www.npl.co.uk/upload/pdf/aml-letter-july2013.pdf . 24 December 2013 . dead .
  18. Web site: Future operation of the National Physical Laboratory (NPL). Retrieved 24 March 2015 . 10 July 2014 . 24 March 2015 . 15 April 2015 . https://web.archive.org/web/20150415210912/https://www.gov.uk/government/collections/future-operation-of-the-national-physical-laboratory-npl . live .
  19. Web site: Notable Individuals. National Physical Laboratory. 2017-10-17. 17 October 2017. https://web.archive.org/web/20171017153447/http://www.npl.co.uk/about/history/notable-individuals/. live.
  20. https://www.jstor.org/pss/769530 Biographical Memoirs of Fellows of the Royal Society
  21. Web site: Professor Sir James Lighthill FRS. Imperial College London. 31 July 2020. 30 September 2020. https://web.archive.org/web/20200930102801/https://www.imperial.ac.uk/fluids-cdt/about/lighthill-lectures/james-lighthill/. live.
  22. Book: Copeland, B. Jack . Colossus: The secrets of Bletchley Park's code-breaking computers . 2006 . Oxford University Press . 978-0-19-284055-4 . 108.
  23. Web site: James (Jim) Hardy Wilkinson. IEEE Computer Society. 6 May 2018. 6 May 2018. https://web.archive.org/web/20180506173943/http://history.computer.org/pioneers/wilkinson.html. live.
  24. Murphy. A. J.. 1976. Marie Laura Violet Gayler. Nature. en. 263. 5577. 535–536. 10.1038/263535b0. 1976Natur.263..535M. 1476-4687. free.
  25. Web site: Research. National Physical Laboratory. 2017-10-17. 17 October 2017. https://web.archive.org/web/20171017152037/http://www.npl.co.uk/about/history/research/. live.
  26. Essen . L. . Louis Essen. Parry . J. V. L. . 10.1038/176280a0 . 1955Natur.176..280E. An Atomic Standard of Frequency and Time Interval: A Cæsium Resonator . Nature . 176 . 4476 . 280–282 . 1955 . 4191481 .
  27. Web site: 60 years of the Atomic Clock. National Physical Laboratory. 2017-10-17. 17 October 2017. https://web.archive.org/web/20171017151756/http://www.npl.co.uk/60-years-of-the-atomic-clock/. live.
  28. Markowitz, W . Hall, R G . Essen, L . Parry, J V L . 1958 . Frequency of cesium in terms of ephemeris time. Physical Review Letters. 1 . 3 . 105–107 . 10.1103/PhysRevLett.1.105. 1958PhRvL...1..105M.
  29. Web site: What Is International Atomic Time (TAI)?. Time and Date. 6 May 2018. 18 July 2020. https://web.archive.org/web/20200718140028/https://www.timeanddate.com/time/international-atomic-time.html. live.
  30. Web site: History of NPL Computing. National Physical Laboratory. 2017-10-17. 17 October 2017. https://web.archive.org/web/20171017154027/http://www.npl.co.uk/science-technology/mathematics-modelling-and-simulation/history-of-computing/. live.
  31. Martin. Campbell-Kelly. Pioneer Profiles: Donald Davies. Computer Resurrection. 44. Autumn 2008. 0958-7403. 19 October 2017. 17 March 2019. https://web.archive.org/web/20190317223708/http://www.computerconservationsociety.org/resurrection/res44.htm. live.
  32. Web site: Smith . Ed . Miller . Chris . Norton . Jim . 2017 . Packet Switching: The first steps on the road to the information society . National Physical Laboratory.
  33. Scantlebury . Roger . 2001 . A Brief History of the NPL Network . https://web.archive.org/web/20030807200346/http://www.topquark.co.uk/conf/IAP2001.html . dead . 2003-08-07 . Symposium of the Institution of Analysts & Programmers 2001 . 2024-06-13 . The system first went 'live' early in 1969 .
  34. John S . Quarterman . Josiah C . Hoskins . 1986 . Notable computer networks . Communications of the ACM . EN . 29 . 10 . 932–971 . 10.1145/6617.6618 . 25341056 . The first packet-switching network was implemented at the National Physical Laboratories in the United Kingdom. It was quickly followed by the ARPANET in 1969. . free.
  35. Computer Freaks . June 22, 2023 . Haughney Dare-Bryan . Christine . Podcast . Inc. Magazine . Chapter Two: In the Air . 35:55 . Leonard Kleinrock: Donald Davies ... did make a single node packet switch before ARPA did.
  36. Book: Hempstead, C. . Encyclopedia of 20th-Century Technology . Worthington, W. . 2005 . . 9781135455514 . 4 June 2020 . https://web.archive.org/web/20211010001453/https://books.google.com/books?id=2ZCNAgAAQBAJ&pg=PA574 . 10 October 2021 . live.
  37. Clarke . Peter . Packet and circuit-switched data networks . 1982 . PhD . Department of Electrical Engineering, Imperial College of Science and Technology, University of London . "As well as the packet switched network actually built at NPL for communication between their local computing facilities, some simulation experiments have been performed on larger networks. A summary of this work is reported in [69]. The work was carried out to investigate networks of a size capable of providing data communications facilities to most of the U.K. ... Experiments were then carried out using a method of flow control devised by Davies [70] called 'isarithmic' flow control. ... The simulation work carried out at NPL has, in many respects, been more realistic than most of the ARPA network theoretical studies."
  38. Book: Gillies. James. Cailliau. Robert. How the Web was Born: The Story of the World Wide Web. 2000. Oxford University Press. 978-0192862075. 25. registration.
  39. Book: Isaacson. Walter. The Innovators: How a Group of Hackers, Geniuses, and Geeks Created the Digital Revolution. 2014. Simon & Schuster. 9781476708690. 237. 27 October 2020. 14 April 2021. https://web.archive.org/web/20210414044223/https://books.google.com/books?id=4V9koAEACAAJ&pg=PA237. live.
  40. Web site: Stewart . Bill . UK National Physical Laboratory (NPL) & Donald Davies . Living Internet . 7 January 2000 . 12 May 2008 . 8 February 2012 . https://web.archive.org/web/20120208035453/http://www.livinginternet.com/i/ii_npl.htm . live .
  41. Web site: Technology of the Internet . live . https://web.archive.org/web/20200131122922/https://www.tnmoc.org/npl-gallery . 31 January 2020 . 3 October 2017 . The National Museum of Computing.
  42. McKenzie. Alexander. 2011. INWG and the Conception of the Internet: An Eyewitness Account. IEEE Annals of the History of Computing. 33. 1. 66–71. 10.1109/MAHC.2011.9. 206443072. 1934-1547.
  43. Davies, Shanks, Heart, Barker, Despres, Detwiler and Riml, "Report of Subgroup 1 on Communication System", INWG Note No. 1.
  44. Web site: 24 April 1990 . Smithsonian Oral and Video Histories: Vinton Cerf . 23 September 2019 . . . Roger Scantlebury was one of the major players. And Donald Davies who ran, at least he was superintendent of the information systems division or something like that. I absolutely had a lot of interaction with NPL at the time. They in fact came to the ICCC 72 and they had been coming to previous meetings of what is now called Datacomm. Its first incarnation was a long title having to do with the analysis and optimization of computer communication networks, or something like that. This started in late 1969, I think, was when the first meeting happened in Pine Hill, Georgia. I didn't go to that one, but I went to the next one that was at Stanford, I think. That's where I met Scantlebury, I believe, for the first time. Then I had a lot more interaction with him. I would come to the UK fairly regularly, partly for IFIP or INWG reasons.
  45. Web site: Internet pioneers airbrushed from history. Scantlebury. Roger. 25 June 2013. The Guardian. 1 August 2015. 1 January 2020. https://web.archive.org/web/20200101062943/https://www.theguardian.com/technology/2013/jun/25/internet-pioneers-airbrushed-from-history. live.
  46. Web site: How we nearly invented the internet in the UK . Scantlebury, Roger . Wilkinson, Peter . New Scientist. 8 January 2020. 2 December 2021.
  47. A. BarberD L.. 1975-07-01. Cost project 11. ACM SIGCOMM Computer Communication Review. 5. 3. 12–15. EN. 10.1145/1015667.1015669. 28994436. free.
  48. Book: Communications Standards: State of the Art Report 14:3 . 9781483160931 . 8 February 2020 . 8 March 2021 . https://web.archive.org/web/20210308005807/https://books.google.co.uk/books?id=3EaeBQAAQBAJ&pg=PA203 . live . Stokes . A. V. . 23 May 2014 . Elsevier .
  49. Web site: EIN (European Informatics Network) – CHM Revolution. www.computerhistory.org. 2020-02-05. 3 February 2020. https://web.archive.org/web/20200203111015/https://www.computerhistory.org/revolution/networking/19/375/2062. live.
  50. Book: Abbate, Janet. Inventing the Internet. 2000. MIT Press. 978-0-262-51115-5. 125. en. 4 June 2020. 10 October 2021. https://web.archive.org/web/20211010001414/https://books.google.com/books?id=E2BdY6WQo4AC&pg=PA125. live.
  51. Book: Hardy. Daniel. Networks: Internet, Telephony, Multimedia: Convergences and Complementarities. Malleus. Guy. 2002. Springer Science & Business Media. 978-3-540-00559-9. 505. en. 4 June 2020. 10 October 2021. https://web.archive.org/web/20211010001414/https://books.google.com/books?id=dRhHPINWo2AC&pg=PT526. live.
  52. Cerf. V.. Kahn. R.. 1974. A Protocol for Packet Network Intercommunication. IEEE Transactions on Communications. 22. 5. 637–648. 10.1109/TCOM.1974.1092259. 1558-0857. The authors wish to thank a number of colleagues for helpful comments during early discussions of international network protocols, especially R. Metcalfe, R. Scantlebury, D. Walden, and H. Zimmerman; D. Davies and L. Pouzin who constructively commented on the fragmentation and accounting issues; and S. Crocker who commented on the creation and destruction of associations..
  53. "it is certainly the first system I know of to combine screen-based word processing, hypertext and e-mail as a service over a general-purpose computer network."
  54. David Yates talks about 'Scrapbook'. https://ghostarchive.org/varchive/youtube/20211212/QqB0w1FkR3o. 2021-12-12 . live. 10 December 2009. National Physical Laboratory via YouTube. 2 December 2021.
  55. which cites
  56. A Formal Interpretation of the MAA Standard in Z. Lai, M. K. F. . Teddington, Middlesex, UK. 1991. NPL Report DITC 184/91. National Physical Laboratory.
  57. [ftp://ftp.inrialpes.fr/pub/vasy/publications/others/Munster-91-a.pdf LOTOS Specification of the MAA Standard, with an Evaluation of LOTOS]. Munster, Harold B. . Teddington, Middlesex, UK. 1991. NPL Report DITC 191/91. National Physical Laboratory.
  58. Specification of the MAA Standard in VDM. Parkin, Graeme I.. O’Neill, G.. 1990. NPL Report DITC 160/90. National Physical Laboratory, Teddington, Middlesex, UK.
  59. Parkin, Graeme I.. O’Neill, G. . 1991. Toetenel, W. J.. Specification of the MAA Standard in VDM. Formal Software Development – Proceedings (Volume 1) of the 4th International Symposium of VDM Europe (VDM’91), Noordwijkerhout, The Netherlands. Lecture Notes in Computer Science. Springer. 551. 526–544. 10.1007/3-540-54834-3_31. Prehn, Søren.
  60. An Implementation of MAA from a VDM Specification. Lampard, R. P. . Teddington, Middlesex, UK. 1991. NPL Technical Memorandum DITC 50/91. National Physical Laboratory.
  61. Minelli, C. & Clifford, C.A.. 2012. The role of metrology and the UK National Physical Laboratory in Nanotechnology. Nanotechnology Perceptions. 8. 59–75.
  62. Web site: 2013. Dimensional Specialist Inspection and Measurement Services : Measurement Services : Commercial Services : National Physical Laboratory. dead. https://web.archive.org/web/20131224152251/http://www.npl.co.uk/huddersfield. 24 December 2013. 23 December 2013. npl.co.uk.
  63. Web site: 2013. Calibration and characterisation of sonar transducers and systems : Products & Services : Underwater Acoustics : Acoustics : Science + Technology : National Physical Laboratory. dead. https://web.archive.org/web/20131224152245/http://www.npl.co.uk/acoustics/underwater-acoustics/products-and-services/calibration-and-characterisation-of-sonar-transducers-and-systems. 24 December 2013. 23 December 2013. npl.co.uk.
  64. Web site: Directors. National Physical Laboratory. en. 2017-10-17. 6 March 2019. https://web.archive.org/web/20190306141958/http://www.npl.co.uk/about/history/directors/. live.
  65. Web site: New CEO for National Physical Laboratory : News : News + Events : National Physical Laboratory . npl.co.uk . 2015 . 1 September 2015 . 6 September 2015 . https://web.archive.org/web/20150906065124/http://www.npl.co.uk/news/new-ceo-for-national-physical-laboratory . live .

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