1. 1 Significance and function of measurement
In order to survive and develop, human beings must know, use and transform nature, and all phenomena or substances in nature have a certain amount of description and embodiment. That is to say, "quantity is an attribute that phenomena, objects or substances can be qualitatively distinguished and quantitatively determined." Therefore, in order to understand the world and benefit mankind, we must analyze and confirm all kinds of "quantities", not only to distinguish the nature of quantities, but also to determine the size of quantities. Measurement is one of the important means to achieve this goal.
Metrology is a science about measurement, and it is a scientific and management activity to realize unit unification, accurate and reliable value and international consistency. In fact, in scientific research, economic activities and social activities, human beings can't do without measurement at any time. As we all know, rulers, scales, electric meters, stopwatches and gas meters are all used for measurement. Measurement has penetrated into all aspects of human work, study and life, and people have unconsciously applied and enjoyed measurement knowledge and technology. Measurement is closely related to national economic construction and various fields of science and technology, whether it is human's food, clothing, housing and transportation, industrial and agricultural production, national defense construction, scientific research, or domestic and foreign trade, measurement is everywhere. Modern measurement has become an important technical foundation of the national economy. In addition, a large number of facts have proved that many important developments in physics have been made on the basis of accurate measurement and testing. And many breakthroughs in cutting-edge national defense technologies are also inseparable from measurement and testing. Therefore, in this sense, the relationship between science and technology and measurement can be summarized as one sentence: "Science and technology should develop and measurement should go first".
Russian scientist Mendeleev once said, "Without measurement, there is no science." Wang Daheng, a famous academician of China Academy of Sciences, said: "Metrology is a science to improve the quantitative accuracy of physical quantities, and it is the foundation and frontier of physics". Therefore, measurement belongs to basic science. Without measurement, science and technology are out of the question. The historical process fully proves that the slow development of measurement technology will seriously hinder the development of science and technology, thus hindering the development of social economy.
1.2 objectives and development of measurement
For a long time, the object of measurement is mainly physical quantity, which gradually extends to engineering quantity, chemical quantity, physiological quantity and even psychological quantity with the progress of science and technology and social development. Professional metrological testing in some high-tech fields, such as bioengineering, medical engineering, environmental protection, information, aerospace, software, etc., is also gradually being formed and strengthened. For example, in bioengineering, people want to know the essence of life and its knowledge of physiology, biochemistry and molecular genetics from protein's control, and are testing and arranging 654.38+0.5 million markers that constitute ribonucleic acid produced in protein. At the same time, the biological computer headed by DNA computer will provide an ideal solution to the problem that the computer processing capacity of silicon chip integrated devices is close to the limit. At this time, the measurement has entered the microscopic field.
Three great technological revolutions in history all fully relied on metrology, which promoted the development of metrology itself. The birth of the steam engine brought the first technological revolution to industry, during which mechanical metrology, thermal metrology and geometric metrology developed rapidly. The second technological revolution marked by the generation and application of electricity further promoted the development of social production. Electromagnetic measurement, radio measurement, temperature measurement, geometric measurement and thermal radiation measurement are further developed, and measurement is brought from the macro world to the micro world. With the establishment and development of quantum mechanics and nuclear physics, the measurement of ionizing radiation has gradually formed. The development and application of nuclear energy and chemical technology led to the third technological revolution. During this period, science and technology and social production developed more rapidly. With the wide application of new technologies such as atomic energy, chemical industry, semiconductor, electronic computer, superconductivity, laser, remote sensing, aerospace, etc., metrology is becoming more and more modern. From classical metrology to a new stage of quantum metrology, metrology is gradually shifting from macroscopic physical benchmark to natural (quantum) benchmark. The new definition of rice and the establishment of atomic frequency standard are of great significance. Accurate measurement of length and frequency promotes the development of modern science and technology. Because the measurement of light speed, the detection of ultra-fine structure of atomic spectrum, navigation, aerospace, remote sensing, laser and many other scientific and technological fields are based on accurate measurement of frequency and length. The so-called fourth technological revolution is a revolution in information technology and energy technology dominated by microelectronics and computers. Many high-tech industries must be based on precision measurement. At present, metrology no longer stays on the basis of previous metrology, but forms an independent discipline-metrology, involving length, temperature, mechanics, electromagnetism, radio, time and frequency, optics, ionizing radiation, acoustics, chemistry and other majors, so-called top ten metrology.
1.3 implementation of measurement method
China is an ancient civilization with a history of 5,000 years, and it is one of the countries with the earliest metrological development and the greatest achievements in the world. As early as more than 2000 years ago, a relatively complete and advanced measurement system was formed. Measurement used to be called "weights and measures" in China, which means the measurement of length, volume and mass. The main measuring instruments used are ruler, bucket and scale. From the unification of "weights and measures" by Qin Shihuang to about 200 years ago, China's measurement technology has been in the advanced ranks. However, during the period from the Opium War to the founding of New China 100, the whole society was in a state of turmoil, which led to the stagnation or even retrogression of the scientific and technological level, including the measurement level. By 1949, there are many units such as English, Japanese, Russian, metric, building ruler and so on, and the national value is chaotic. After the founding of New China, the Party and the government attached great importance to the development of metrology. In order to unify the national measurement system, the State Council issued the Order on Unified Measurement System on June 25, 1959/KLOC-0, and determined that the metric system at that time, later the international system of units, was the national basic measurement system. 1985 On September 6th, the National People's Congress Standing Committee (NPCSC) passed the People's Metrology Law of China. At the same time, 1985, China joined the international organization for legal metrology (OIML), which indicates that China's metrology work has been brought into the legal management track, and the metrology laws and regulations are basically complete, which has been in line with international legal metrology.
1.4 Establishment, responsibilities and tasks of China Institute of Metrology
The seven basic quantities in the international system of units are length, mass, time, current, thermodynamic temperature, quantity of matter and luminous intensity. Their units are meters, kilograms, seconds, amperes, kelvin, moles and Candeira. The main derived quantity is derived from the relation function of the basic quantity. The basic quantity and the derived quantity are just like the branches of a big tree, which together constitute the metrological scientific system.
Since the founding of New China, China's metrology has developed rapidly. 1955, State Bureau of Metrology and China Institute of Metrology (hereinafter referred to as Institute of Metrology) were established. As the national metrological scientific research center and legal metrological technical institution, Metrology Institute is the source of national quantity traceability from beginning to end, the national legal metrological institution and the core of metrological technical work in China.
Main tasks undertaken by Metrology Institute:
Study, establish and maintain national measurement benchmarks and standards, and copy unit values; Conduct international comparison to ensure that the benchmark value is consistent with international standards.
Carry out tracking research on measurement benchmarks and standards, make use of the latest scientific and technological achievements, continuously expand the measurement range and frequency band of measurement benchmarks and standards, and improve the accuracy and automation.
Carry out research on measurement theory, value transfer method and * * *, basic and key measurement technology.
Implement the value transfer work, organize the value comparison of important domestic laboratories, and ensure the unity of national values.
According to the needs of science and technology, national economy and social development, research on metrology technology in new fields will be carried out.
To undertake technical management work such as national metrological certification, technical assessment and various professional metrological technical committees; Technical work of type identification and type approval of domestic and imported measuring instruments; Technical guarantee of metrological arbitration in import and export trade: technical work of quality certification and laboratory evaluation.
Training a metrology team with high quality and strong scientific research ability, establishing and constantly improving the quality system of metrology institute, strictly controlling the quality of metrology certificates and improving the ability to serve customers are the goals that metrology institute has been persisting in and striving for since its establishment and development.
Conduct pre-job training for new employees and master the basic knowledge of measurement; Encourage people with certain scientific research ability to continue their studies and study in domestic universities or foreign metrology institutions to improve their professional level; Our college holds various training courses such as English, network programming, technical regulation writing, etc. from time to time, with various forms. At present, nearly 20% of the existing technical personnel in Metrology Institute have master's degree or above.
According to the requirements of ISO/IEC17025:1999, the Institute of Metrology has established a relatively perfect quality system and started to operate. The structure of quality system of Metrology Institute is shown in Figure 2, including quality manual, program documents and work instructions. It meets the requirements of ISO/IEC17025:1999 and contains all its quality elements.
1999 Metrology Institute passed the on-site evaluation of calibration and testing laboratories organized by the National Accreditation Committee of Chinese Laboratories, and passed the calibration item 127, with 23 testing items, *** 150. In 2000, it passed the on-site evaluation of calibration and testing laboratory of Metrology Institute by National Accreditation Committee of China Laboratory. In May, 2003, the Institute of Metrology completed the transformation from Guideline 25 to ISO/IEC17025:1999, and successfully completed the supervision, evaluation and expansion. In September, 2004, it passed the re-evaluation of China National Laboratory Accreditation Committee. So far, the Institute of Metrology has been able to conduct 407 external calibrations and 208 tests. The number of laboratory accreditation items changes with time, as shown in Figure 3. Laboratory accreditation projects cover length, thermal engineering, mechanics, electricity, radio, optics, ionizing radiation and medicine, engineering optics, engineering technology and many other fields. To provide calibration and testing services for all sectors of society to ensure the accurate and unified national values.
With the continuous development of calibration market, in order to serve customers more comprehensively, 1998 Metrology Institute added calibration items on the basis of the original verification test. At the same time, according to the requirements of ISO/IEC17025: 1999, all certificates have been fully considered in format, content and security, and have been revised in different versions of1999, 200 1, 2002 and 2004. At present, eight new certificates have been basically formed, including verification, notification of verification results, calibration (in Chinese, English and Chinese), test (in Chinese and English) and test report. This version of the certificate has the characteristics of complete information, strong anti-counterfeiting function, rigorous description of the verification period, unique contents and methods to inform customers, and novel certificate style. After a period of practice, it has not only been recognized by customers, but also been used as a model certificate by many provincial technical institutions.
On June 1 day, 2003, the instrument receiving and dispatching hall of the Institute of Metrology was officially opened, and the corresponding instrument receiving and dispatching software also began to run. The new software aims at "facilitating customers, simplifying processes, improving work efficiency and minimizing the workload of inspectors". The customer only needs to send the instrument to the receiving and dispatching hall, and once the inspection information is entered, the relevant personnel can call it several times. The software makes full use of database and network technology to analyze and combine the input information, automatically generate the contents of the first page of the certificate, monitor the detection status of the measuring instruments/instruments submitted for inspection in real time, and publish them in the whole hospital. The software has powerful functions such as statistics, query, charts and so on, which provides the necessary first-hand basic data for the metrology institute to strengthen process management and improve service quality.
Second, legal measurement.
The content and significance of measurement are very extensive, and legal measurement is an important concept in measurement, which is essential and vital to industrial and agricultural production, national defense technology and people's life. Since the implementation of Metrology Law for 20 years, Metrology Institute, as a national legal metrological technical institution, has established and continuously improved metrological standards. Strengthen international cooperation and exchanges to improve international status; Implement compulsory verification to ensure the safety of people's lives; Entrusted by the General Administration of Quality Supervision, Inspection and Quarantine, it undertakes the task of measuring standard assessment and measuring instrument type approval test.
2. 1 measurement benchmark
The national measurement standard is the measurement system that defines and reproduces the unit quantity, the basis for the national unification of the unit quantity, and the national treasure. Although the weights and measures have been unified since Qin Shihuang, before 1949, there was no physical reference-the reference used to unify the values. The development of modern benchmarking in China began in the late 1950s. Under the leadership of the State Science and Technology Commission, the Institute of Metrology successfully developed the first national standard of surface roughness in 196 1. By 1998, the state officially approved 1 1 high-precision measuring system developed by national metrology research institute as the measurement benchmark. These benchmarks have played a very important role in implementing legal measurement management, unifying national measurement units, carrying out modern scientific and technological research and developing modern national defense construction.
As the highest research center of metrology science in China, Metrology Institute has completed a large number of high-level scientific research projects and established the initial national benchmarks and standards through the hard struggle and hard research of several generations of metrology scientists. Since then, in the face of the new demands put forward by social development, we have kept up with the pace of economic construction and scientific and technological development and the trend of high-tech development in the world, and our research level has been continuously improved, the number and coverage of measurement benchmarks and standards have been continuously expanded, and our position in the international arena has also been constantly rising. Most of China's benchmarks, sub-benchmarks and the country's highest social public measurement standards were born and preserved here. In order to cooperate with the implementation of the national metrology law, in the past 20 years, the Institute of Metrology has used these benchmarks and standards to transmit values, ensuring the unity and reliability of domestic values and the consistency with international values.
From 199 1 to now, about 109 measurement standards and standards have participated in the technical transformation, and some of them have achieved very good results after the transformation, and the measurement range and accuracy have been greatly improved.
(1) water three-phase point bottle
The triple point of water is the only reference point of thermodynamic temperature, and it is also an important defined fixed point of ITS-90 international temperature scale. It is of great significance in thermodynamic temperature measurement, reproduction of international temperature standards and actual temperature measurement. In order to strengthen the in-depth study of water triple point, in recent years, the Institute of Metrology has established a new manufacturing system for high-quality water triple point containers and developed a series of high-quality water triple point containers with different structures and sizes. On this basis, the effects of ice bridge, environment, water source, freezing method and water purification on the triple point temperature of water are studied. These theoretical and experimental studies have improved the reappearance level of water triple point and filled the blank of domestic research. The newly developed water triple point container participated in the International Key Comparison of Water triple point container (CCT-K7) organized by the International Bureau of Metrology. The reproducibility of technical indicators is better than 0.03mK, and the expanded uncertainty is 0. 16mK(k=2.69, p=0.99).
(2) Acoustic benchmark of coupled cavity reciprocity method
The sound pressure standard of reciprocity method for measuring the coupled cavity is established in 1965. Before 1990, the technical transformation was carried out to improve the calibration accuracy of 1 inch laboratory standard condenser microphone from 50 Hz to 2000 Hz to 0.05 dB (k = 3). After the technical transformation of the benchmark in 2000, the main technical indexes of the benchmark reached the requirements of international standards, and the automation of complex reciprocity calibration was realized. In July, 2002, the benchmark participated in the international CCAUV. U-k 1), and the comparison results are very satisfactory. In March, 2003, I participated in CCAUV. A-K3) (3 1.5 Hz ~ 3 1.5 kHz).
(3) 20MN reference dynamometer
The force measuring room of the Department of Mechanics is one of the earliest laboratories established by the Institute of Metrology. 20MN benchmark dynamometer developed and preserved in our laboratory is the largest super-heavy precision dynamometer in China at present. For the first time, hydrostatic lubrication technology is applied to the working cylinder plug system with single cylinder structure, and the manufacturing technology is difficult, and all parts are localized. 1990 passed the appraisal of the former State Bureau of Technical Supervision and reached the international advanced level. 1992 was awarded the national benchmark with strong strength, and 1996 won the first prize of national scientific and technological progress. Its application provides accurate test means for scientific research and technology development of large-scale engineering projects, improves the detection level of safety stress state of engineering structures and high-rise buildings, and creates necessary conditions for improving the overall accuracy of aerospace technology. The accuracy of force is better than 1× 10-4, the variation of force is better than 1× 10-4, and the sensitivity limit is better than 2× 10-5.
1990 10, the Institute of Metrology made a strong value comparison with Japan's NRLM. The force value of two 20MN benchmark machines in China and Japan is about 1× 10-4, and the force value of 20MN benchmark machine in China fluctuates in the order of 10-5, which is one order of magnitude better than that of Japanese 20MN machine, which fully shows the excellent performance and advanced level of hydrostatic lubrication working cylinder plug system.
(4) single-phase power frequency electric energy
The single-phase power frequency electric energy standard was developed by the Institute of Metrology and passed the appraisal organized by the State Bureau of Technical Supervision in February of 1990+. 65438+ 1996 was approved as the national benchmark by the State Bureau of Technical Supervision in July, and it is responsible for the calibration, detection and value transmission of electric energy meters of 0.0 1 and above in China.
It adopts the original double-bridge power comparator technology, and its main equipment includes a double-bridge power comparator and a set of current-voltage transformers. It has the advantages of high precision, wide range and good stability. The total uncertainty of this benchmark is 15× 10-6(k=3), which is in the international leading level. 1992 won the first prize of scientific and technological progress in our institute, the second prize of scientific and technological progress in technical supervision bureau, and 1993 won the second prize of national scientific and technological progress.
1996 Metrology Institute carried out constant temperature transformation on the reference laboratory, so that the annual temperature of the laboratory basically met the requirements. At the same time, we also purchased 15 thermocouples needed by the device to ensure the normal operation for quite some time in the future.
1998-2000, 65438 people participated in the international comparison organized by CCEM and led by NIST, and achieved good measurement results, which were at the same level as those of the United States, Germany and Canada.
(5) Reference of pulse waveform parameters
Pulse waveform parameters include: pulse amplitude, rise time, overshoot, pre-overshoot, top roughness, damping oscillation, depression, pulse width, period, triangular wave linearity and so on. The traditional method is to visually inspect the waveform on the screen by the operator, which is not only affected by the human eye resolution, oscilloscope linearity, screen focus and noise, but also by the distortion of the waveform itself, so the measurement accuracy is low. 1986 The pulse waveform parameter benchmark developed by Metrology Institute is mainly composed of high-quality broadband sampling oscilloscope, high-speed pulse source and computer system with data acquisition. To undertake the value transmission of national pulse instruments. The system has the characteristics of powerful function, rich test software, stable and reliable performance, high degree of automation, advanced design idea and high performance-investment ratio. It has reached the advanced level in the world in the field of automatic measurement of pulse parameters and is in a leading position in China, which has played an important role in pulse measurement in China. /kloc-0 won the third prize of national scientific and technological progress in July, 1989.
From 1996 to 1998, the system was technically reformed, the data acquisition box was redeveloped, the computer system was replaced, the test software was rewritten, and the oscilloscope calibration system was improved, which greatly improved the detection ability and data processing efficiency. At present, the technical indexes of the benchmark are: pulse amplitude: 65438+1100mv ~ 200v; The measurement uncertainty is 0.05%; Pulse rise time: 25ps ~1ns; Measurement uncertainty: 1%+5ps.
With the development of digital electronic technology, it is necessary to measure higher-speed pulse signals, and the development of pulse parameters is developing in the direction of high-speed and information. At present, the pulse condition parameter group is cooperating with Beijing University of Technology to study "Study on the Establishment of National Reference of New Pulse Condition Waveform Based on NTN Technology", which can improve the existing national reference of pulse condition waveform parameters with rising time of 2 1ps by 7ps.
(6) Spectral radiance and radiance benchmark
The reference device was developed by the Institute of Metrology in 1975, and was approved as a national reference by the State Bureau of Metrology in 1986. 1978 won the national science and technology conference award, and 1990 won the second prize of scientific and technological progress of the State Bureau of Technical Supervision. The whole set of reference device is easy to use and has stable and reliable performance. This benchmark has provided the highest measurement standard for the measurement of spectral radiance and illuminance in China for more than 20 years. It is one of the important benchmarks of national optical metrology and an international key comparison project determined by the International Bureau of Metrology (BIPM). The measurement of spectral radiance and illuminance is widely used in photoelectric, aerospace, national defense, lighting engineering, remote sensing and medical and health fields, which has great social benefits.
The benchmark device has been technically reformed twice. The modified reference device extends the high-end working temperature of high-temperature blackbody to 3200K, which provides a stronger short-wave ultraviolet signal for spectral radiance measurement. In order to solve the problem of low sensitivity of the detector system in ultraviolet and near infrared bands, an ultraviolet sensitive photomultiplier tube R3896 and a large area 2mm× 10mm refrigerated PbS detector are used. Aiming at the problem of large temperature measurement error of AC photoelectric pyrometer, DC photoelectric pyrometer and temperature standard lamp are adopted, and the temperature standard is extended by monochromatic brightness comparison method. Compared with the previous temperature measurement methods, the uncertainty of temperature measurement is improved.
1990 and 200 1 participated in the international comparison of spectral irradiance on behalf of more than a dozen countries that participated in CCPR organization in China. The comparison results of 1990 show that the spectral irradiance measurement in China is generally at the international advanced level, especially in the visible range. The international comparison of 200 1 is in progress.
2.2 International exchanges and cooperation
(1) sign MRA.
In order to meet the requirements of WTO to eliminate technical barriers to trade, at the meeting held by BIPM in June 1999 10 in Paris, France, the presidents of national metrology institutes of 38 metric convention member countries and representatives of two international organizations * * * signed the Agreement on Mutual Recognition of National Metrology Basis, Standards and Calibration and Metrology Certificates issued by the National Metrology Institute. MRA is authorized by the International Metrology Congress, drafted by the International Metrology Committee (CIPM) and coordinated by the International Bureau of Metrology (BIPM). Pan Biqing, president of Metrology Institute, was entrusted by AQSIQ to sign MRA agreement on behalf of China. The transitional period of MRA agreement is four years, and it was formally implemented on June 65438+1 October1.
The goal of MRA is to establish an open and transparent comprehensive measurement system, provide reliable quantitative information about the comparability of national measurement standards for users all over the world, and thus provide a technical basis for the government and other parties to sign international trade, business and legal agreements. The core content is that under the auspices of BIPM, under the responsibility of CIPM 10 Advisory Committee (CCs), and with the cooperation of regional metrology organizations (RMOs), international comparisons of metrology standards are planned, including key comparisons and auxiliary comparisons, thus giving the national standards the equivalence.
The signing of MRA is conducive to China's economic opening to the outside world, international scientific and technological exchanges and international trade, and at the same time improves the authority and "gold content" of calibration and measurement certificates of metrology institutes. On the other hand, the signing of MRA puts forward strict requirements for the establishment, transformation and normal maintenance of measurement standards in China, and puts forward high standards and new requirements for the operation of quality systems such as experimental environment, management system, personnel quality and resource allocation of measurement technical institutions in China.
(2) Sign other mutual recognition agreements.
Sino-Dutch mutual recognition
1999 on behalf of the Institute of Metrology, the Quality Weighing Laboratory of the Institute of Metrology and the Netherlands National Institute of Metrology conducted on-site evaluation of the testing ability of non-automatic weighing instruments. Technical personnel of both parties shall conduct technical training and exchange, coordinate the testing methods of both parties, and discuss and determine the contents of the mutual recognition agreement. 1999165438+1October 3rd, an agreement on mutual recognition of type test results of non-automatic weighing instruments was signed in Shenzhen. The mutual recognition of the type test reports of non-automatic weighing instruments between China and the Netherlands has prevented the non-automatic weighing instruments from repeating the type test before entering the other country's market, which has created favorable conditions for promoting the export of non-automatic weighing instruments from China to Europe.
Mutual recognition between China and Germany
From April to August of 20001year, in the project "Mutual Recognition Agreement between AQSIQ and German Federal Institute of Physics and Technology (PTB) on Type Test Reports of Non-automatic Weighing Instruments and Weighing Sensors", the quality weighing laboratory and dynamometer laboratory respectively designated laboratories for the Mutual Recognition Agreement on Type Test Reports of Non-automatic Weighing Instruments and Weighing Sensors, participated in and completed Chinese hardware equipment and English technical materials (including the dean's statement in the quality manual, traceability system, etc.). In June of the same year, Metrology Institute accepted the on-site technical evaluation of three experts from PTB on the quality weighing laboratory and force measuring laboratory of mechanical department, environmental laboratory of engineering electronics department, emc laboratory of radio department and North China United laboratory. In August, the Institute of Metrology sent two professional technicians to participate in the expert group of the General Administration (6 persons) and went to PTB, Germany to complete the on-site evaluation of laboratory peers and exchange of technical documents, which laid a technical foundation for the final signing of the Sino-German mutual recognition agreement.
At the signing ceremony of 29 Sino-German cooperation projects held in the Great Hall of the People in Beijing on 10 +0, 2006, German Chancellor Gerhard Schroeder attended, and Director Xuan Xiang of the Metrology Department of AQSIQ and Manfred Kochsiek, Vice President of the German Federal Institute of Physics and Technology (PTB) formally signed this agreement. The signing of the mutual recognition agreement on type test reports of non-automatic weighing instruments and weighing sensors between China and China is conducive to promoting German non-automatic weighing instruments and weighing sensors to enter the European market and seize market share.
The mutual recognition of international measurement of type test reports meets the needs of economic globalization. At the same time, it has expanded the international influence of China's legal metrology work, improved the international reputation of China's metrology technical institutions, and promoted the integration of China's legal metrology work with the international community.
(3) Participate in international comparison.
The first part of MRA is the equivalence between national measurement standards, and its technical basis is a set of results obtained after a certain period of key comparison between CCs, BIPM and RMOs. Key comparison by CCs or BIPM is called CIPM key comparison, and key comparison by RMOs is called RMO key comparison.
The reference value obtained by CIPM key comparison is called "key comparison reference value". The so-called "equal validity of measurement benchmarks" refers to the consistency between these benchmarks and key comparison reference values. The equivalent validity of each national measurement standard can be quantitatively expressed by two values: the deviation from the key comparison reference value; And the uncertainty of deviation (confidence level is 95%). The equivalent validity between two national measurement standards is expressed by the difference between them and the reference value and the uncertainty of the difference (the confidence level is 95%).
Fig. 6 shows an embodiment of key comparison. The big circle in the middle is the comparison hosted or implemented by CCs and BIPM, and the small circle around it is the comparison hosted or implemented by regional metrology organizations. In addition, there are some direct bilateral comparisons, which are conducted around large and small circles and metrology institutes participating in international or regional key comparisons.
Since the signing of the 1999 mutual recognition agreement, the Institute of Metrology has actively participated in the key comparison work organized by CIPM and BIPM. Up to now, 62 key comparisons (excluding reference substances) and 2 other bilateral or multilateral comparisons have been completed. Some comparison results are very good, reaching the international advanced level. For example, in the quantized Hall resistance comparison (CCEM-K 10) completed at the end of 2004, the results of draft A show that only the measurement results of China Metrology Institute (NIM), German Metrology Institute (PTB) and American Metrology Institute (NIST) fall on the average line, which provides a strong proof for improving China's position in the international metrology field.
(4) Participate in regional comparison.
The result of RMO key comparison is that some metrology institutes have participated in both CIPM and RMO comparison, which is related to the reference value established by CIPM key comparison. The uncertainty of comparison data is shared according to the number of measurement institutions participating in the two comparisons and the quality of the results reported by these measurement institutions. The purpose of RMO key comparison is to extend the measurement equivalent validity established by CIPM key comparison to more nmi, including those that belong to the International Conference on Metrology (CGPM) or the economy.
As one of the important members of Asia-Pacific Metrology Organization (APMP), Institute of Metrology actively participates in regional comparison and supports the development of metrology in the Asia-Pacific region, which is also the unshirkable responsibility and obligation of Institute of Metrology. Over the years, the Institute of Metrology has actively participated in regional comparisons on the basis of international key comparisons. By 2004, * * * had participated in 10 APMP key comparison and 9 bilateral and multilateral comparisons within the region.
(5) Organizing training courses on metrology technology for developing countries.
From 1990 to now, the Institute of Metrology has undertaken 1 1 training courses on metrology technology for developing countries, and trained nearly 300 metrology personnel in length, thermal engineering, mechanics, electromagnetism and other disciplines for many developing countries such as Vietnam, Malaysia, Mongolia, Thailand and the Philippines. By holding the "Training Course on Metrology Technology for Developing Countries", they have deepened their understanding of Metrology Institute. During the training, more than one agreement 10 was signed with Singapore, Malaysia, Turkey and other countries, and more than one cooperation and R&D project 10 was signed. In addition, it has been invited to hold training courses abroad for many times, with more than 100 participants.
By holding training courses on metrology technology for developing countries, it provides a convenient way to trace the relevant metrology standards, such as batteries, resistors, standard capacitors, function meters, hardness blocks, dynamometers, high-temperature lamps, power meters, etc. , applicable to national metrology institutions such as Iran, Vietnam, North Korea and Mongolia. At the same time, the quantum department also carries instruments to assist Singapore, Brunei, Malaysia, South Korea and other countries to measure the local absolute gravity acceleration; During the period from 1994 to 1996, the Institute of Metrology assisted the Malaysian National Institute of Metrology in establishing the high temperature benchmark and standard, and formed a high temperature laboratory with initial scale. Through the exchange of this training course, the reputation and popularity of China Metrology Institute in developing countries have been improved, and it has also contributed to the development of metrology in developing countries.
2.3 Compulsory verification
All working measuring instruments that are listed in the Catalogue of Working Measuring Instruments for Compulsory Verification in People's Republic of China (PRC) and directly used for trade settlement, safety protection, medical and health care and environmental monitoring, as well as those used for law enforcement and supervision in the above aspects, must be subject to compulsory verification, and the most common ones are gas meters, water meters and electric meters. In order to cooperate with the implementation of metrology law, the Institute of Metrology has combined the verification of electric energy meter with the verification of "three medical sources", improved its own metrology level, and made great contributions to ensuring the implementation of national metrology supervision and management, reducing disputes in various fields such as commerce and trade, and safeguarding the interests of the country and consumers.
With people's growing concern for health, advanced medical equipment has developed rapidly, and more and more measuring methods and instruments have been applied to medical care, thus forming a branch of "medical measurement", which involves the measurement, analysis and monitoring of temperature, pressure, quality, ultrasound, ionizing radiation, biomechanics, brain current, blood composition, cardiac computer monitoring and other related parameters. Among the compulsory measuring instruments in China, the measuring instruments used by Chinese medicine account for.