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Abstract:
Point at present situation of measuring small pulling forcegauge inmetrological service,small pulling forcegauge calibration device was developed,so some matterswhensmallpulling forcegauge is measured usingWeight,for example ,heavy working intensity,unablezeroed and full scale range cannot be measured ,can be solved.
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Aiming at the problems of low efficiency, accuracy and poor reproducibility in manual measurement of weight quality, the work flow of weight measurement, the stability of mass comparator, the motion control of three-dimensional manipulator and the positioning accuracy of loading and unloading are studied. The basic principle of PLC servo control system is analyzed, and a set of control system of weight automatic verification device based on PLC is designed and developed. Taking CX programmer as the development platform, the control system is established by using PLC and ladder diagram programming language. The automatic control of the whole process of weight loading and unloading and the automatic detection of weight quality are realized. The overall debugging and experimental verification of the system are carried out. The results show that the control system has the advantages of simple structure, high efficiency and avoiding human error, and improves the automation level and reliability of weight verification.
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Anechoic room and hemi-anechoic room provide necessary acoustic environment for various acoustic tests, mainly including frequency range of free sound field, spatial range of free sound field and background noise. Anechoic room and hemi-anechoic room absorb the sound wave incident on the wall and reduce the reflected sound by laying sound-absorbing materials in the room, so as to create a free sound field environment in the anechoic room and hemi-anechoic room. This paper mainly introduces the principle and method of calibrating the anechoic chamber and the semi anechoic chamber by means of the inverse square law method, and the process to analysis data of the free filed. This paper provides experience for improving the measurement accuracy of free filed to the anechoic room.
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The influence factors of the measurement error of fuel dispensers mainly come from ambient temperature, flow rate of oil gun, standard metal gauge and oil and gas recovery system. In this paper, the effects of ambient temperature, flow rate of oil gun, standard metal gauge and oil and gas recovery on the error of indication value of fuel dispensers are analyzed through multiple groups of comparative experiments. Experiments show: the verification volume of standard metal gauge is lower than the actual volume when the gasoline temperature is lower than the environment temperature in summer. However, the verification volume of standard metal gauge is higher than the actual volume in winter. The error value will be bigger in the large velocity. Due to the volatility of gas is caused by the structure of standard, different standard shows different error value. It will gives less oil when the gas recovery is activated. The larger the gas liquid ratio is, the bigger the error value is.
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Based on the spatial geometry analysis, a mathematical model is established to measure the kingpin angle, with the detection mechanism of positioning parameters measured studied, and a verification device of four-wheel alignment designed. The device uses the spherical hinge structure to make the simulated kingpin tilt back and inward independently, avoiding the principle error caused by interference in the synthetic motion. The dual-axis inclination angle sensor is used to measure the positioning parameters accurately. According to the analyses of the finite element modal of the device by ANSYS software, the results show that the stiffness and the inherent frequency and vibration model of the first six orders meet the requirements of the structure. The zero error of the kingpin angle and the error of each wheel location parameters from the test basically met the requirements of the calibration specification and verified the feasibility of the device.
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In torque verification, the fluctuation of torque value over time is not a known common function, and it is vital to explore the trend of its change and fluctuation for torque verification and dissemination of value of quantity. To explore the fluctuation characteristic of the torque sensor, the influence of medium- and long-term stability on the change of torque value in torque measurement is investigated, and a neural network is used to train the detection data under given conditions to predict the torque value at other time points. The torque value data obtained under strictly controlled experimental conditions for the last 12 years were used for training and analysis, the accuracy and reliability of the model were demonstrated by cross-validation, the torque value of the next calibration cycle was predicted, and the probability that the torque value of the next cycle meets the long-term stability of 0.03 level was finally calculated to be greater than 71.8%.
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To grasp the metrological performance indicators of the BeO optically stimulated luminescent (OSL) dosimetry system and verify whether it meets the needs of personal dose monitoring, the OSL dosemeter containing BeO optically stimulated luminescent detectors was placed in and irradiated with X-ray and γ-ray reference radiation fields. Performance test research on nonlinear response, coefficient of variation, energy response, angular response, and repeatability were carried out for the personal dose equivalent Hp(10). The nonlinear response ranged from 0.92 to 1.05 in the dose range of 50 μSv to 1 Sv, and the coefficient of variation ranged from 0.55% to 4.8%. The energy response ranged from 0.71 to 1.01 in the energy range of 33 keV to 1.25 MeV. The angular response ranged from 0.97 to 1.22 in the range of 0° to ±75° angle of incidence. The irradiation dose of 1 mSv, 5 mSv and 10 mSv were repeated 8 times, and the corresponding dose repeatability were 0.99 - 1.00, 0.99 - 1.00 and 0.97 - 1.00, respectively. The results showed that the BeO OSL dosimetry system meets the requirements of the IEC 62387-2020 standard and can be used for personal dose monitoring.
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Low field nuclear magnetic resonance has gradually become the mainstream method for measuring solid fat content, which is an important index to qualify cocoa butter, margarine and other oils because it is simple, rapid and solvent free. However, Low field nuclear magnetic resonance direct method is a relative method, which requires the instrument to be calibrated using a glycerol trioleate/glycerol tristearate mixture. In this paper, the development and the principle of Low field NMR are introduced, the traceability and the stability of the glycerol trioleate/glycerol tristearate solid fat content reference material are studied, the measurement in different temperature are compared and the determination of the value was confirmed.
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Very high frequency omnidirectional range (VOR) is an important radio signal in the field of aviation navigation. Its phase parameters are used to characterize the bearing information. The basic principle of VOR signal and the measurement method of azimuth are introduced, and the comparison results of VOR phase parameters in 6 reference laboratories in China are given. The evaluation of domestic VOR phase parameter measurement capability is completed. It lays a foundation for ensuring the unification of quantity and value of aviation navigation parameters in China.
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Monitoring, analyzing and measuring the real-time change of RF signal plays a key role in optimizing the signal spectrum efficiency. Real time spectrum analyzer uses digital fluorescence analysis technology to observe, measure and analyze time-varying signals, which has become an important means to monitor transient signals. The basic technical principle of real-time spectrum analyzer is introduced, and the calibration methods of real-time analysis bandwidth and minimum pulse width amplitude ratio of full intercept are studied and proposed. According to the main functional characteristics of real-time spectrum analyzer, the calibration methods of real-time analysis bandwidth and minimum pulse width amplitude ratio of full intercept are experimentally verified, and their uncertainty is analyzed and evaluated.
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: 4-octylphenol, 4-nonylphenol, ethinyl estradiol, hexestrol and dienestrol are typical endocrine-disrupting compounds, which are found in water, soil and food. So, there is a wide demand for the certified reference materials. In this paper, the purity of the five organic compounds were analyzed by differential scanning calorimetry (DSC), and joint research was carried out by high performance liquid chromatography (HPLC) and thermal gravimetric analysis (TGA). The results showed that the purity of 4-octylphenol, 4-nonylphenol, ethinylestradiol and hexaestrol could be determined by differential scanning calorimetry. The purity determined by DSC are well consistent with the HPLC method. No obvious endothermic curve of dienestrol was observed by DSC, and decomposition of dienestrol was found in the TGA study. So, it is not applicable for the purity analysis of dienestrol by DSC method.
Abstract:
To improve measurement efficiency, calibration laboratories gradually employ the automatic measurements system to replace the manual measurement. At present, the data directly generated by the automatic measurement system focuses on the presentation of the measurement results, but lacks the key information elements required by ISO-17025 for the original records and certificate reports. For measurements of weights in small nominal value, the weights always easily drop from the comparators, which may interrupt the measuring progress and end up generating an incomplete record need to be splicing and restructuring by operators. During the data analysis and processing progress, the automatic measurement system still requires manual work of calculating, typing environmental conditions data, and other required information of weights or clients into record sheets. In this paper, we focus on measurements of weights in small nominal value, a data analysis and processing method based on the automatic measurement system was proposed to automatically split and recombine the original data, identify the unqualified results, and reduces the interference of human factors. Valid original records and certificate reports can be automatically generated by this method to increase efficiency of mass measurements.
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This report investigates the technology list and entity list of U.S. export control, conducts demand analysis on literature resources for institutions included in the entity list, and analyzes literature that has been restricted from ordering. It is found that conference resources account for most restricted literature. Meanwhile, articles from two sensitive fields, military technology, and nuclear technology, as well as the publication of the United States account for the majority of restricted literature. Based on the analysis, this paper puts forward some suggestions on collection construction, such as increasing the collection rules of literature construction, constructing special literature data through multiple channels, further expanding the types of collection resources, and using new technologies to promote the transformation of collection resources from using advantages in resource quantity to transforming precise and comprehensive connection and discovery of new resources. Finally, we discussed the situation and challenges of technology competition that China is facing, as well as the importance and strategic support of measurement literatures in measurement research innovation.
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Organic analysis is an essential part of chemical metrology, and is closely related to food, clinical and environmental sectors. Organic Analysis Working Group (OAWG) is one of the nine technical working groups under the Consultative Committee for Amount of Substance: Metrology in Chemistry and Biology (CCQM), International Committee for Weights and Measures (CIPM). In December 2020, OAWG issued the Strategic Plan for 2021~2030. Learning the strategy of OAWG is of great importance to understand the status of global organic chemical metrology, follow international development trends and provide reference for strategic planning in China.
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Salofamide mesylate is mainly used to treat Parkinson's disease. A LC/MS method was developed for the determination of genotoxic impurities ((S) - 4 - ((1-amino-1-oxopropane-2-methyl) amino) methyl) in safinamide mesilate. The sample was dissolved in methanol, separated on YMC-Triart C18 column (4.6mm×100 mm, 3μm), mobile phase: water (containing 0.1% formic acid) -methanol (containing 0.1% formic acid), gradient elution, and finally detected with a mass spectrometer detector. Under the condition of selected chromatography, genotoxic impurities can separate well. The LODs was 0.76 mg/kg and the LOQs was 1.53 mg/kg. Standard recovery rate was 98.5%~99.90% with relative standard deviations of 0.83%~2.10%. The linear response range was between 1.53~30.54 ng/mL (R2 >0.99). The results showed that the method was sensitive, accurate, reliable and suitable for screening of genotoxic impurities ((S) - 4 - ((1-amino-1-oxopropane- 2-methyl) amino) methyl) in safinamide mesilate.
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Water soluble ions are major components in airborne particulate matters, and play a key role in the source appointment of particulate matters. This article reviews monitoring methods, instruments and standards for water soluble ions in particulate matters, as well as recent progresses of metrological researches on the monitoring methods. Traceability issues still exist in both offline and online monitoring methods, as reference materials with the form of particulate matters deposited on the filter are lacking for the quality control of the pre-treatment of filter samples in offline methods, and traceability for online methods has not yet been established. Considering the urgent demands from environmental monitoring realm, immediate developments should be carried out on reference materials on filters and online calibration systems.
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Tungsten telluride magnetoresistive material is famous for its unsaturated magnetoresistance effect. Information storage and the manufacture of magnetic sensor devices based on this also represent an important direction of magnetoresistance research. The doping method can change the magnetic and electrical properties of the material. In order to explore whether tungsten telluride magnetoresistive materials can obtain excellent performance through silver doping, a detailed analysis of how to choose the doping method and why choose silver as the doping element is discussed. And a method for the gentle preparation of bulk silver-doped tungsten telluride magnetoresistive materials is established. A new self-service flux sintering method is used to prepare three typical silver-doped WTe2/Ag materials. The characterization and evaluation of phase, valence state, structure, and accurate measurement of magnetoresistance performance have obtained. These results indicate that the excellence of the silver doping method which is selected, the prepared WTe2/Ag not only has reliable material quality, but also effectively improves the magnetoresistance effect, which make it easier to realize the control conditions when testing the highest value. The measured magnetoresistance is 502.3% at 5 K and 14 T, which is 50% higher than undoped. The magnetoelectric performance is greatly improved by compared with other elements, which is of positive significance for the optimization design and practical application of electromagnetic devices.
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The total radiant flux is one of UV LED radiant characteristics. One way to measure the quantity of total radiant flux is deduce from the quantity of total spectral radiant flux (TSRF). In recent years, the National Institute of Metrology have made progress in measurement of TSRF. In the middle of the research, to ensure the measurement uncertainty in near UV zone, the TSRF calibration facility and an horizontal-type goniospectroradiometer are used respectively to measure TSRF and total radiant flux of UV LEDs. Comparative results show that these two measurement ways are equivalent considering the uncertainties. the TSRF calibration facility’s uncertainty in near UV zone is reasonable and reliable.
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With the gradual maturity of laser gyro manufacturing technology and the breakthrough of locking and other major issues, laser gyro goniometer has become a high-precision and high-sensitivity multi parameter goniometer. This paper carries out a comprehensive test for its metrological performance for the first time, and comprehensively analyzes the main error sources of laser gyro goniometer. In this paper, the main sources of the system error of the laser gyro goniometer are analyzed in detail, including the installation error of the laser gyro, the non horizontal error of the turntable and the unstable error of the rotating speed. The simulation analysis and estimation of the error caused by each factor are made. At the same time, the random error of the laser gyro goniometer is analyzed by using the classical Allan variance method, The results show that the uncertainty of comprehensive angle measurement is 0.4 ", and the angle measurement error is better than ± 0.5″.
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The rapid analysis technology of near-infrared spectroscopy is one of the main methods to detect the ethanol content in gasoline. And the selection of the spectral spectrum is important for the prediction accuracy of the rapid analysis model. In this study, a fast analysis method of near-infrared spectroscopy based on effective characteristic spectrum was established to improve the accuracy of detection of ethanol concentration in gasoline. The near-infrared spectra of gasoline with different concentrations of ethanol were compared, then the effective characteristic spectrum of ethanol molecules in gasoline were determined to be 4524.183~5044.869 cm−1 and 5985.961~7108.329 cm−1. Choose the best pre-processing method for near-infrared spectroscopy, and use the full-spectrum and effective characteristic spectrum of near-infrared spectra for modeling and analysis, respectively. The relevant parameters of quantitative analysis model with effective characteristic spectrum are as follows: the root mean-squared error of cross-validation (RMSECV) is 0.5849, internal cross-validation correlation coefficient (${{R}}_{\text{CV}}^{\text{2}}$) is 0.9991, the root mean-squared error of prediction (RMSEP) is 0.6090, and the external verification correlation coefficient (${{R}}_{\text{P}}^{\text{2}}$) of the prediction set is 0.9989. Compared with the full-spectrum model, the RMSECV is reduced by 30.27 %, the RMSEP is reduced by 18.58%. In conclusion, the quantitative analysis model established by using the characteristic spectrum has higher accuracy and can meet the needs of rapid analysis of ethanol concentration in gasoline.
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In order to meet the test and calibration requirements of the flow tritium ionization chamber, radioactive reference gases DT with different activity concentrations should be prepared. With the aid of the moderator and resin purification system of heavy water containing tritium in CANDU6 reactor of Qinshan No.3 Nuclear Power Plant, the DT preparation device of ultra-wide concentration radioactive reference gas was developed based on the absolute measurement of liquid scintillation counting-the activity concentration of moderator obtained by electrolysis method, the analysis of hydrogen isotope abundance of electrolysis gas by mass spectrometry and PVT principle index dilution method. The device was designed with a catalytic-oxidation-liquid scintillation counting verification unit and a tail gas collection-reuse processing unit.At the same time, isotope infiltration, inner wall electroplating and other measures were adopted to reduce the adsorption-memory effect of the device wall during sample preparation. The device has the advantages of small size, wide range of activity concentration, small memory effect, small adsorption effect of low concentration DT, small cross-contamination and low uncertainty. The volume activity concentration range of the prepared radioactive reference gas DT (under standard conditions) is 5.97×104~1.0×1014 Bq/m3. The prepared radioactive reference gas DT can meet the requirements of testing and calibration of different types and uses of mobile tritium ionization chambers in China.
Abstract:
High purity α-arbutin reagent was used as raw material which was further identified and confirmed by MS/MS, IR, UV-vis, nuclear magnetic resonance, melting point, optical rotation, etc.. The chromatographic purity of α-arbutin reference standard was determined by high performance liquid chromatography (HPLC) coupled with fluorescence detector (FLD). Moisture and ignition residue determination were carried out according to the guideline specified in Volume IV of the Pharmacopoeia of the People's Republic of China 2020 Edition, respectively. The residual solvents were determined according to the procedure specified in the Safety and Technical Standards for Cosmetics. The purity of α-arbutin reference standard was then calculated by mass balance method and the certified value of α-arbutin is 99.87% with an expanded uncertainty of 2.46% (k=2). Homogeneity and stability tests were carried out with HPLC-FLD after packaging. The α-arbutin reference standard with a high purity, accurate value and stability can provide technical support to cosmetics quality and safety tests in China.
Abstract:
Pump drive loop heat pipe energy recovery device was an air conditioning energy recovery device. It integrated the advantages of intermediate heat medium and loop heat pipe heat exchangers and suitable for complex piping layout. In order to study the performance of the device, the experimental system of pump drive loop heat pipe energy recovery device was set up and heat exchange、temperature efficiency、performance coefficient three performance evaluation coefficient were proposed and the effects of temperature difference、mass flow rate、heat exchange area and working medium four factors on the performance of the device were considered. By testing the heat exchange、temperature efficiency、performance coefficient under different temperature difference、mass flow rate、exchange area, the relationship between them and optimal operation scheme were analyzed. It provided guidance and reference for the design and operation of such devices.
Abstract:
The quantity of microorganisms in drinking water is one of the important indicators for water quality and safety. In order to understand and evaluate the ability of domestic testing laboratories which carry out the detection of Escherichia coli (E.coli) in drinking water, National Institute of Metrology(NIM) developed proficiency testing sample for the quantification of E.coli in drinking water and organized a proficiency testing. According to GB/T 5750.12-2006 Standard examination methods for drinking water—Microbiological parameters, 11 participating laboratories participated the proficiency testing and determined the CFU or MPN value of E.coli in lyophilized samples reconstituted in sterile water.by using the filtration membrane method and enzyme substrate methodThe statistics indicates that the results of all the participating laboratories are satisfactory. The E.coli quantitative proficiency testing samples are homogeneous and stable, which can meet the requirement of proficiency testing for quantification of E.coli in drinking water and truly reflect the ability of participating laboratories.
Abstract:
Bisphenol A is one of the most widely used industrial compounds in the world. Because it can be used in the production and manufacture of a variety of polymer materials, it is ubiquitous in actual production and daily life. But bisphenol A is also a typical environmental endocrine disruptor, which can cause disorders of human metabolism and reproductive function, and in severe cases, it can cause various cancers. With the increasing emphasis on the addition of bisphenol A in various industries in recent years, the detection methods of bisphenol A have also been continuously innovated. This article reviews the advanced detection technology and methods at home and abroad, combs and summarizes the research progress of bisphenol A detection, and puts forward the prospects for the development of bisphenol A detection in the future.
Abstract:
Radiotherapy level ionization chamber dosimeter is the main measuring instrument for radiotherapy in hospital, and it is also the national compulsory verification measuring instrument. The accuracy of its dose measurement is the key to carry out precision radiotherapy. In order to ensure the accuracy and unity of the quantity value, from 2019 to 2020, National Institute of metrology, China, as the leading laboratory, organized the comparison of the national (60-250) kV X-ray air kerma. A total of 11 units or laboratories participated in the comparison. All reference laboratories established 60 kV, 100 kV, 135 kV, 180 kV and 250 kV reference radiation qualities. This comparison adopts the "petal" comparison method to complete the calibration measurement of two transfer standard ionization chambers in the radiation field, and obtain the calibration factor and measurement uncertainty under different radiation qualities. The comparison results show that the normalized deviation of each reference laboratory is less than 1, and the comparison results are satisfactory.
Abstract:
Digital PCR (dPCR) is an absolute quantitative technique of nucleic acid, which is widely used in transgenic and gene detection. In order to ensure the accuracy and reliability of digital PCR measurement results in China, 16 laboratories were tested using transgenic plasmid DNA samples. The comparison results showed that the difference between the ratio of foreign gene to internal copy number (<25%) to evaluate the measuring ability of the laboratories. The 16 laboratories were all within the acceptable range, and there was no significant difference among different digital PCR platforms. Due to the influence of plasmid conformation, the absolute copy number content of plasmid DNA measured in 7 laboratories was significantly lower than the reference value. It is suggested that when using digital PCR for quantitative measurement of plasmid DNA copy number, it should be confirmed whether the conformation of plasmid has an effect on amplification.
Abstract:
In July 2021, the Consultative Committee for Amount of Substance: Metrology in Chemistry and Biology (CCQM) issued the Strategy Document for 2021-2030, delivering its mission of advancing the global comparability of chemical and biological measurement standards and capabilities. This article summarizes the highlights of the Strategy Plan, with an aim to learn about the priorities of future development, underpin strategic planning in China as well as optimize the structure and mode of international cooperation to boost the development of metrology in chemistry and biology in China.
Abstract:
Hollow shaft angle encoder automatic calibration was achieved using a continuous full-circle angle standard developed by the National Institute of Metrology as a standard angle generator, a two-dimensional slideway clamping system to fix the encoder stator, and data acquisition software based on the LabView development platform. The clamping system tackles with the manual positioning difficulty due to high starting torque and provides continuous automatic calibration in the 360° full-circle range, which improves the testing efficiency and reduces the sources of uncertainty. The encoder repeatability is better than 0.8″ after using clamping system.
Abstract:
Arsenic and antimony are typical anionic pollutants. Events of arsenic and antimony pollution often occur due to the wide exploration of arsenic and antimony mineral resources and the heavy use of pesticides and additives with arsenic and antimony. The speciation analysis of arsenic and antimony is of great significance for environmental monitoring and pollution regulation. In this paper, the developed analytical techniques for arsenic and antimony were summarized in detail. The paper focused on the development of on-site analysis techniques. Meanwhile, two developing issues were put forward, including the speciation analysis and on-line monitoring technique.
Abstract:
Aiming at the excessive temperature interval between the zinc fixed point (419.53℃) and the aluminum fixed point (660.32℃) in the 90 international temperature scale (ITS90), an Al-Cu fixed point (Cu 33wt%, 548.16℃) was developed as an auxiliary fixing point. Independently developed radiation thermometers RT9032 was used to test the melting and freezing temperature values of Al-Cu fixed points. There are three ways to select the temperature value of the Al-Cu fixed point: 1. The average value of the melting platform, 2. The point of inflection (POI), and 3. The upper limit (UL). The research results show that: different selection methods have no significant difference in the melting temperature, the maximum temperature difference is 34mK, and the repeatability of the Al-Cu fixed point is within 18mK. Therefore, the Al-Cu fixed point (melting point) can be used as an auxiliary fixed point other than the ITS-90 fixed point.
Abstract:
The dialysate concentration is generally expressed by the dialysate conductivity monitoring value, and its accuracy and stability are the guarantee for the patient to achieve adequate dialysis treatment. According to the national metrology technical specifications, use the hemodialysis machine detector to test the conductivity parameters of the hemodialysis machines in the medical institutions in the province. The results showed that the qualified rate of hemodialysis machine conductivity parameter detection was 99.9%. By analyzing and discussing the causes of conductivity inaccuracy, it can provide reference for the clinical management of hemodialysis machines in hospitals at all levels, and improve the quality assurance capability of medical equipment.
Abstract:
Evaporation loss is an important indicator of oil quality. The current industry standard NB/SH/T0059-2010 "Lubricating Oil Evaporation Loss Determination (Noacke Method)" in non-wood alloy Noacke B method has the advantages of non-toxic, can simulate the actual working conditions of the engine, accurate test results and so on, and is widely used in the industry. This paper studied the influence of different factors including sample addition, heating temperature, heating time and pressure difference of vacuum pump on the experimental results and the introduced uncertainty in the process of B method measurement. When the sample amount changed within 65 g±0.1 g, the test result changed to ±0.019%. The fluctuation of the heating temperature within 245.2℃±0.5 ℃ may cause the evaporation loss test result to change within ±0.27%. The change of heating time every 5s may cause the test result to change by less than 0.02%. The measurement result change caused by the pressure fluctuation of the vacuum pump at 20 mmH2O±0.2 mmH2O is ±0.04%. The uncertainty introduced by the sample amount, heating temperature, heating time, and vacuum pump pressure difference is 0.011%, 0.16%, 0.01%, and 0.02%, respectively, and the expanded uncertainty introduced by each influencing factor is 0.32% (k=2).
Abstract:
Carbonaceous aerosol has important impact on climate change and environmental pollution. The accurate measurement of carbonaceous aerosol can effectively reduce the uncertainty of aerosol radiative forcing estimation and atmospheric source apportionment, which could further provide scientific support for the government control policies on climate change and reduction of source emission. This review summarizes the measurement methods and influencing factors of carbonaceous aerosol worldwide, with a focus on the research progress and limitations of existing standardized protocols and reference materials. The review emphasizes that the development of carbonaceous aerosol reference materials is still limited which needs further study. Based on the current research progress, this review also proposes future challenges and research directions from various aspects including the traceability of reference materials, the selection of representative species of organic carbon and elemental carbon, the configuration of OC/EC mixed reference materials, and the impact of carbonate carbon. The review aims to provide a reference for future study of carbonaceous aerosol reference materials.
Abstract:
The accuracy of the dry biochemistry analyzer has a direct impact on the clinical diagnosis results. In view of the lack of its calibration specifications, the calibration specifications are formulated. Through the analysis of the technical principles and calibration methods of the dry biochemistry analyzers, the main measurement characteristics and specific calibration methods were determined, and a representative dry biochemistry analyzer model was selected for experimental verification. According to the calibration method, the verification result of the dry biochemistry analyzer meets the requirements of the determined measurement characteristics. The "Calibration Specification of Dry Biochemistry Analyzers" was successfully formulated, which promoted the standardization and standardization of the traceability of the dry biochemistry analyzers.
Abstract:
The general characteristics of the threaded connection of inertial devices are small size and high assembly accuracy.In this paper,a set of small-size screw tightening test device is developed to solve the problems of large pre-tightening force error and low control precision during the assembly process of small-size screws. Through the tightening process experiment of TC4 titanium alloy screws, the influence of the tightening strategy on the value and dispersion of pre-tightening force is analyzed, including torque-control method and angle-control method.The influence of threshold torque and step by step tightening on pre-tightening force is further studied. The results show that angle-control method can improve the control preload precision by about 7% compared with torque-control method. The selection of threshold torque of angle-control method has great influence on the consistency of preload. Step by step tightening can improve the control precision of torque-control method and angle-control method on pre-tightening force.
Abstract:
Microchip´s PIC24FJ128GC006 is used as the central processing unit, and LabVIEW is used as the host computer software development platform to develop a DHT8X digital temperature and humidity sensor data acquisition system. The multi-channel digital signals are collected by the single-chipmicrocomputer, and the collected data is transmitted to the upper computer through RS232. The data acquisition system designed by LabVIEW performs data display, processing, storage, and generates data records. It has been verified that the device has simple operation, accurate data reading and good running performance.
Abstract:
Off-site law enforcement comes as an important means for investigations into unlawful acts of motor vehicles. The metrological performance of monitoring devices, however, is directly linked to the accuracy and impartiality of law enforcement. The paper sorted out monitoring devices for off-site motor vehicle law enforcement used by traffic police, environmental protection and traffic competent authorities as well as their metrological technical criteria, and studied the features and existing verification and calibration methods of such monitoring devices. Besides, suggestions as to the verification and calibration methods of monitoring devices, for example the detection system for vehicle honking, were proposed.
Abstract:
As one of the important performance parameters of signal source, it is of great significance to measurement the signal source voltage standing wave ratio(VSWR)accurately. Based on the study of the signal source basic structure and the mechanism of “RF off”, this paper analyzes the influence of“RF on”and“RF off” on the measurement results of the signal source VSWR. With vector network analyzer as the measurement equipment, this paper studies the measurement methods of signal source VSWR in different modes. The experimental results show that the passive device measurement method under the condition of “RF off” can be used for the signal source with fast closing mode. While, the frequency offset measurement method under the condition of “RF on” can be used for the completely closing mode.
Abstract:
According to the measurement method in Appendix A of JJF 1815-2020 " Calibration Specification for Class Ⅱ Biosafety Cabinets ", the source of uncertainty components of each standard was analyzed, and themeasurement uncertainty evaluation method for biosafety cabinet personnel, product and cross-contamination protection (potassium iodide method) has been successfully established,and the uncertainty of the measurement results was evaluated, when the inclusion factor k is 2,the expanded uncertainty of personnel protection of the biological safety cabinet is 34%, the expanded uncertainty of product protection is 33%, the expanded uncertainty of cross-contamination protection is 32%, which can be used for the traceability of biological safety cabinet personnel, products and cross-contamination protection parameters and the standardization of measurement uncertainty evaluation methods.
Abstract:
As an important rehabilitation physiotherapy equipment and non-invasive nerve regulation technology, repetitive Transcranial Magnetic Stimulation (rTMS) plays an important role in the treatment of mental diseases and the regulation of brain function. rTMS uses pulsed magnetic field to activate human brain, the magnetic induction intensity and output frequency of pulsed magnetic field determine the safety and effectiveness of stimulation. Starting with reviewing the development of TMS, the technical principle of rTMS was introduced firstly, and then the research path of its measurement was described in detail. In this paper, the distribution of pulsed magnetic field generated by typical stimulation coil was obtained through simulation, which could specify the approximate position of the maximum value point of magnetic induction intensity in grey matter. By wounding measurement coil and performing necessary experiments on it, the possibility of detecting pulsed magnetic field by electromagnetic induction principle was improved. The measurement method developed in this paper could not only be used for the detection of rTMS in use, but also serve cutting-edge scientific research fields such as neuro modulation, which would contribute to the implementation of the implementation of the Healthy China 2030 Plan.
Abstract:
Hexabromocyclododecanes (HBCDs) is one group of brominated flame retardant which is mass-produced and widely used. Hexabromocyclododecanes (HBCDs) also belong to new persistent organic pollutants (POPs). Accurate analysis and determination of HBCDs in environmental matrix are of great significance to the monitoring and control of environmental pollution for their wide distribution and large content span in environment. This paper summarized the pollution distribution of HBCDs in sediments all over China. On the basis of literature research, the key technologies such as pretreatment, separation and detection of HBCDs in sediment and related matrixes were compared and analyzed. In addition, by investigating the source of HBCDs reference materials, the issue of accurate and quantitative traceability of HBCDs was discussed, and the future measurement and monitoring work of HBCDs was put forward.
Abstract:
The single sheet tester is a common equipment used for measuring the magnetic properties of electrical steel, the measuring methods have been well defined by the national standard GB/T 13789-2008 (idt IEC 60404-3:2002) “Methods of measurement of the magnetic properties of electrical steel sheet and strip by single sheet tester”. With newly developing on the high grade products such as domain refined, thinner and low loss materials, in practice, the additional loss created by yokes of single sheet tester has become an unignored factor in the measurement. The current national standard requires only that yokes should have low and constant loss when it was manufactured, but no further treatment for the loss introduced by yokes. This paper studied the measuring method of the loss created by yokes of single sheet tester, and analyzed its effect on the measuring result of the magnetic properties of electrical steel based on the data of yokes loss for different points of magnetic polarization, then methods to eliminate the yokes loss of single sheet tester have been proposed.
Abstract:
Purity assessment for peptide is the key to build metrological traceability for the measurement value of peptide in the fields of clinical chemistry, pharmaceutical chemistry, food chemistry, etc. Besides mass balance approach, nuclear magnetic resonance, and hydrolysis approach, organic elemental analysis is a new technique for assessing the purity of peptides in chemical metrology. However, this technique is rarely reported in detail. In this paper, a technique for peptide purity assessment based on nitrogen, sulfur analysis has been established. With an oxytocin material as a typical sample, nitrogen, sulfur contents in the sample were quantitatively analyzed, followed by the substraction of nitrogen, sulfur contents in the structurally related impurities obtaining nitrogen, sulfur contents in the main components. With the atomic numbers of nitrogen, sulfur in an oxytocin molecule and molecular weight information, purity value of the oxytocin study material can be assessed. Compared with the measurement results from authentic mass balance approach, the relative standard deviation is less than 1%. The result of impurity correction organic element analysis technique established in this paper is accurate, reliable, and therefore can be used to purity assessment for peptide reference material.
Abstract:
Proton radiotherapy has become a precision radiotherapy technique owing to the superiority of Bragg Peak on the depth-dose distribution. This review provides the details of three detectors applying in reference dosimetry as well as the corresponding limitations in clinical proton modalities. Further discussions on the corrections and improvements when measuring proton beam dosimetry have been proposed combined with Monte Carlo techniques. Also the state-of-the-art determination on micro-dosimetry of proton beams has been summarized extensively.
Abstract:
At present, Wearable ECG monitoring equipment is lack of special metrology technology regulation. Based on the relevant standards and metrology technology methods of traditional ECG medical equipment, this paper studies the performance evaluation method of Wearable ECG monitoring equipment. Six types of Wearable ECG monitoring and measuring devices from different manufacturers are measured by using Wearable ECG simulator, and the performance evaluation method of these devices is explored. The results show that the accuracy of the main performance parameters of the Wearable ECG monitoring equipment can be evaluated to a certain extent through the above ways, and the traceability of some parameters can be realized.
, Available online  , doi: 10.12338/j.issn.2096-9015.2020.0166
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Abstract:
In mmwave technology a low frequency is always multiplied to generate a much higher frequency. Phase noise will be also increased and phase noise test will be more important in mmwave band. It is limited with spectrum analyzer method because of some reasons. And phase noise analyzer can only cover up to 50 GHz in a single unit. After the basic introduction of phase noise test technology in mmwave band two external mixer method is provided. Result shows that with this method we can get a stable test result.