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2021 Vol. 42, No. 10
Published: 2021-10-28
 
1265 Calibration and Traceability of Responsivity for Terahertz Array Detector
GAO Yan-jiao,FANG Bo,DENG Yu-qiang,YU Kang-jie,QI Cen-ke,CAI Jin-hui
DOI: 10.3969/j.issn.1000-1158.2021.10.01
A method for irradiance responsivity calibration and traceability of a terahertz array detector is proposed. Firstly, each pixel of the array detector is shift to scan the center of the terahertz irradiation field one by one, and then effective pixels, overheated pixels and dead pixels is discerned. The response of the effective pixels is normalize to obtain the relative irradiance response of the array detector. Secondly, the center pixel is used to measure the terahertz irradiation field. Make sure the scanning area larger than the terahertz spot size, so that the total power of the terahertz radiation is fully measured. The terahertz power response values of the central pixel and other effective pixels are obtained.Finally, a Golay Cell detector is calibrated with a standard terahertz power meter as reference, and then the traceable measurement of terahertz power is extended to microwatt-level. The integrated response value measured by the array detector is calibrated with the Golay Cell. And thus the absolute irradiance response of the array detector is obtained. The relative expanded uncertainty of the measured irradiance responsivity is 20% (k=2), and the measurement result can be traceable to the national terahertz radiant power standard.
2021 Vol. 42 (10): 1265-1270 [Abstract] ( 259 ) HTML (1 KB)  PDF (2232 KB)  ( 601 )
1271 The Method for Measuring the Positioning Accuracy of Confocal Raman Microscope
DING Xiang,FU Yan-zhe,LI Fei,LIU Wen-li
DOI: 10.3969/j.issn.1000-1158.2021.10.02
Confocal Raman microscopy (CRM) usually acquires images by scanning samples point by point. The positioning error of three dimensional stages may cause the image distortion and the mismatch between the image and the real sample. A simple method was proposed to measure the positioning accuracy of the Raman imaging. The measurement accuracy was enhanced by using the method of Fermi function fitting. A testing phantom was fabricated by coating a 70nm thick layer of chromium pattern onto the surface of a piece of silicon substrate. A commercial CRM was tested and its positioning repeatability is 0.2μm. Results show that the method is capable of measuring the positioning accuracy of CRM and it has the advantages of simplicity and stability.
2021 Vol. 42 (10): 1271-1274 [Abstract] ( 273 ) HTML (1 KB)  PDF (1472 KB)  ( 556 )
1275 The Inner Diameter Measurement and Uncertainty Evaluation on the Piston Cylinder of Piston Gas Flow Standard Device
LI Pei-jing,CUI Li-shui,LI Chun-hui
DOI: 10.3969/j.issn.1000-1158.2021.10.03
Due to the limit of the structural characteristics of piston cylinder for the measuring instrument, a measuring method for the inner diameter of the piston cylinder with three coordinate measuring machine was proposed. Taking the piston cylinders with nominal inner diameters of 19mm, 45mm, and 140mm as examples,the measurements for the inner diameter,external diameter and thickness of the piston cylinder were carried out. The difference of the inner diameter of the piston cylinder obtained with different measurement methods was analyzed and compared, and the reliability of the three coordinate measuring machine for measuring the inner diameter of the piston cylinder was verified. In addition, the influence of the shape characteristics of the piston cylinder on the uncertainty of its inner diameter measurement was analyzed. The measurement results of the inner diameter of the piston cylinder is 18.999mm, 44.983mm, 139.975mm respectively, and the relative measurement uncertainty is 0.016. %, 0.015%, 0.010%.
2021 Vol. 42 (10): 1275-1281 [Abstract] ( 281 ) HTML (1 KB)  PDF (1684 KB)  ( 202 )
1282 Laboratory Test and Optimization of Ultrasonic Flow Measurement Device
LIU Dun-li,CAI Qin,HU He-ming
DOI: 10.3969/j.issn.1000-1158.2021.10.04
In order to improve the accuracy of online flow calibration for large diameter pipeline, a set of ultrasonic flow measurement device is established. The probe installation technical process and geometric parameter measurement method are optimized for practical use. The flow rate model is studied and flow rate calibration under different probe protrusion state is done in the laboratory. The configuration of double-plane 4-path is installed for a DN400 pipe, and three probe protrusion states are tested to get a best solution based on flow error analysis. The experiments shows that the probe protrusion state has a significant impact on the flow measurement error of the device, and flow measurement results increases with the increase of probe insertion depth. The full contraction state is with the best linearity, and the practical installation with this state can get the best flow measurement accuracy with 0.2 level after a coefficient correction. The ultrasonic flow measurement device can meet the accuracy requirements of online flow calibration for 1.0 level large diameter pipeline after laboratory optimization.
2021 Vol. 42 (10): 1282-1287 [Abstract] ( 231 ) HTML (1 KB)  PDF (1775 KB)  ( 147 )
1288 Research on Micro Friction Testing Technology of Micro-electro-mechanical System
WU Cui-hong,YU Bo,ZHAO Jing,LIU Xiao-han,WU Xin-yu
DOI: 10.3969/j.issn.1000-1158.2021.10.05
In order to solve the problem of micro-friction in micro-electro-mechanical systems(MEMS), a micro-friction test technology based on light reflection was proposed. The basic principles and implementation steps of the test method were discussed, the test prototype was developed, the complete process of measurement and calibration of the test system was analyzed in detail, and finally the measurement data and curve of the test system were obtained. Through the micro-friction experiment test on the Cu-Si and Al-Si surfaces, the micron-level micro-friction coefficients of the Cu-Si and Al-Si surfaces were obtained. It provides a basis for the understanding and design of the micro-mechanisms motion characteristics.
2021 Vol. 42 (10): 1288-1293 [Abstract] ( 224 ) HTML (1 KB)  PDF (1738 KB)  ( 222 )
1294 Apparatus for Density Measurement with Direct-driven Vibrating Tube Method
WEI Chuan-zhe,PAN Jiang,SONG Xia-hong,XU Xu
DOI: 10.3969/j.issn.1000-1158.2021.10.06
A density measurement apparatus based on the direct-driven vibrating tube method was developed. Under the condition that the vibrating tube was filled with vacuum and ethanol, the instrument constants were calibrated at temperatures from 260K to 360K and pressures from 0.1MPa to 20MPa. The performance of the device was validated by measuring the liquid densities of isopropanol and sec-butanol, and the experimental results were compared with literature data. The deviation of experimental data for isopropanol and sec-butanol from literature data were within ±0.2% and ±0.3%, respectively. It was verified that the accuracy of the device met the requirements of density measurement. The results could serve as the references for other researchers.
2021 Vol. 42 (10): 1294-1298 [Abstract] ( 212 ) HTML (1 KB)  PDF (1650 KB)  ( 239 )
1299 Chaotic Singular Spectrum Analysis Based on Improved Phase Space Reconstruction Algorithm and Its Application
ZHANG Li-guo,LIU Wan,ZHANG Shu-qing,LIU Hai-tao,DONG Wei,SONG Shan-shan
DOI: 10.3969/j.issn.1000-1158.2021.10.07
An improved algorithm for phase space reconstruction is proposed for the problem of embedding dimension and delay time uncertainty in chaotic singular spectrum analysis. The joint criterion is evaluated by the supplementary criterion, and the Cao algorithm is improved. An improved embedding dimension stability criterion embedding dimension using the improved Cao algorithm, can quickly and accurately determine the value of the embedding dimension, with accuracy and efficiency; The method of obtaining the delay time based on the maximum joint entropy based on symbol analysis can reduce the amount of calculation and reduce the error. The superiority of the proposed method is verified by numerical comparison experiments. The method is applied in the early fault identification of rolling bearings. The results show that the chaotic singular spectrum can clearly see the pattern distribution of different fault signals and realize the feature extraction of mechanical fault signals. Provide a new and effective way for early diagnosis of mechanical failure.
2021 Vol. 42 (10): 1299-1306 [Abstract] ( 261 ) HTML (1 KB)  PDF (3721 KB)  ( 214 )
1307 Research on Degradation Process and Continuity Reliability of Rolling Bearing Vibration Performance
CHENG Li,XIA Xin-tao,MA Wen-suo
DOI: 10.3969/j.issn.1000-1158.2021.10.08
To investigate the relationship between the degradation process and the continuity reliability of rolling bearing vibration performance, the degradation model of rolling bearing vibration performance is proposed based on maximum entropy method and similarity method; then the continuity reliability model of rolling bearing vibration performance is established based on the maximum entropy method and poisson process; Finally, the Gray relation analysis is performed on the performance degradation sequence and the continuity reliability sequence of the rolling bearing. The experimental results show that the proposed degradation model of rolling bearing vibration performance can effectively identify the degenerative state of rolling bearings, and there is a clear gray relationship between the evolution processes of the continuity reliability and the degradation process of rolling bearing vibration performance, the credibility level exceeds 80%.
2021 Vol. 42 (10): 1307-1315 [Abstract] ( 245 ) HTML (1 KB)  PDF (2598 KB)  ( 171 )
1316 Research on Automated Dissemination of Primary Standard for Pneumatic Piston Gauges
ZENG Lin,YANG Yuan-chao,YUE Jin,HUANG Qian
DOI: 10.3969/j.issn.1000-1158.2021.10.09
Based on the transducer-aided crossfloat (TAC) method, an automated calibration system for piston gauges has been developed and improved. The components and function of the calibration software based on the LabVIEW are introduced. The reliability of applying the automated calibration system on the dissemination of primary standard for pneumatic piston gauges is studied by comparison test against the traditional crossfloat method (CF). The transducer coefficient (γ) could be treated as 1 if the deviation is so small that the product of the deviation and the relative pressure difference (β) is less than 10-6. For the counter-pressure pneumatic piston gauges with the measurement upper limit of 7MPa, the fitting data of the full-scale and half-scale indicate that the pressure deformation of the piston has a certain degree of nonlinearity, so full-scale calibration should be carried out for the high-pressure piston; The thermal effect of the PG7607 piston base causes a piston temperature measurement error of 0.33 ℃, resulting in a pressure measurement error of 3×10-6, which is non-negligible for the primary standard; The calibration results for the 180kPa, 360kPa and 3MPa piston gauges determined by the automated system and the traditional method differ from each other are about 10%, 1% and 2% of the standard uncertainty, which verify the high reliability of the automated calibration system.
2021 Vol. 42 (10): 1316-1322 [Abstract] ( 216 ) HTML (1 KB)  PDF (2908 KB)  ( 165 )
1323 Measurement and Analysis of Environmental Vibration of Plain Ground in Advanced Measurement Experimental Area
WANG Hong-jun,LIU Zhi-hua,DONG Yu-ping
DOI: 10.3969/j.issn.1000-1158.2021.10.10
The measurement and analysis of environmental vibration in plain land is of great significance for the construction of advanced measurement laboratory, which can be used to guide the applicability of the construction site selection of advanced measurement laboratory and the design of environmental vibration control. Taking the location of the advanced measurement experiment area of NIM as an example, the environmental excitation method is used to test the environmental vibration of the advanced measurement experimental area, and the 1/3 octave band analysis method is used to process the velocity time history data. The results show that: under steady-state conditions, the vibration index of the plot in the frequency band of 1~100Hz is lower than VC-F standard, but the maximum vibration velocity in the frequency band of 12.5~20Hz is close to or greater than VC-G standard. It is found that the vibration source in this frequency band comes from the random vibration caused by the loading and unloading of goods at the container terminal between 21:00 and 10:00 the next day, and the removal of the container terminal will help to meet the requirements of the laboratory vibration control standard VC-G. affected by the operation of a large bus under the specified conditions, the best setback distances required by the environmental vibration standards VC-G, VC-F and VC-E in the frequency band of 8~25 Hz are 195m, 182m and 160m respectively. The test and analysis of the environmental vibration of the surrounding road traffic under different conditions can accurately determine the best setback distances for the construction of different environmental vibration standards laboratories.
2021 Vol. 42 (10): 1323-1327 [Abstract] ( 242 ) HTML (1 KB)  PDF (1878 KB)  ( 678 )
1328 Research Progress on Broadband Electromagnetic Angular Vibration Calibration System
TANG Bo,HE Wen,LIU Ai-dong
DOI: 10.3969/j.issn.1000-1158.2021.10.11
On the basis of analyzing laser interferometry, the system composition, principle of measurement, data processing and measurement range for the angular vibration measurement method of A-type and B-type laser interferometry are described systematically, and it is especially pointed out that the performance of angular vibrators directly affects the angular vibration calibration result. On this basis, the research status and progress of angular vibrators are analyzed at home and abroad, and the specifications, application scopes and limitations of different types are pointed out. Finally, the electromechanical coupling equation of broadband angular vibrators is established, and the key techniques involved, such as design technology of a moving component with high torsional resonant frequency, design technology of a magnetic circuit structure with strong and uniform air gap magnetic field and design technology of an adjustable electro-viscoelastic-support device, are analyzed in depth, and the corresponding research ideas and suggestions are given.
2021 Vol. 42 (10): 1328-1334 [Abstract] ( 271 ) HTML (1 KB)  PDF (1011 KB)  ( 520 )
1335 Analysis and Research of Reconstruction Algorithm Based on Near-field Acoustic Holography
CHEN Lu,GUO Shi-xu,WANG Yue-bing,ZHENG Hui-feng,XU Ao-xuan
DOI: 10.3969/j.issn.1000-1158.2021.10.12
The wide variety of acoustic holography algorithms and the requirements of different applications, the three algorithms based on Fourier transform, statistically optimized and equivalent source model are analyzed by combining finite element simulation and numerical simulation. The influence of source frequency, reconstruction distance, sampling distance and regularization methods on reconstruction accuracy are found, and their computational efficiency is compared. Experiments are carried out in open water. The results show that: with the sound source frequency and the reconstruction distance increases, the number of sampling points decreases, the reconstruction accuracy decreases gradually. In the low frequency region, the statistical optimal near-field acoustic holography combined with L-curve regularization method has the best sound field reconstruction effect; the acoustic holography reconstruction based on equivalent source method has the highest accuracy, but it is easy to produce virtual images; the acoustic holography algorithm based on Fourier transform is seriously affected by the reconstruction distance, but the reconstruction speed is excellent, and the sound source positioning is accurate.
2021 Vol. 42 (10): 1335-1342 [Abstract] ( 293 ) HTML (1 KB)  PDF (4114 KB)  ( 352 )
1343 Research on Measurement Technology of Power Frequency Short-circuit Current of Transformer
MEI Guo-jian,LI Chuan-sheng,WANG Jia-fu,ZHAO Ye-ming,DONG Ping,SHAO Hai-ming,YAO Yan
DOI: 10.3969/j.issn.1000-1158.2021.10.13
Aiming at the requirements of transformer power frequency short-circuit current measurement, the external integral Rogowski coil technology and fiber-optic current sensing technology are studied. The low-frequency mathematical models of the two sensors are established which based on MATLAB/Simulink to calculate the response characteristics of the sensor to the power-frequency short-circuit current. The results show that the measurement accuracy of the Rogowski coil for the power-frequency short-circuit current is affected by its lower cut-off frequency. If the cut-off frequency is lower, the measurement accuracy will be higher. The optical fiber current sensor can theoretically accurately reproduce the power frequency short-circuit current. Multiple current sensors are used for the field comparison test of the transformers power frequency short-circuit current. The results show that the current waveforms measured by the AC/DC current comparator, the fiber-optic current sensor, and the Rogowski coil with a lower cut-off frequency of 0.02Hz agree well, the measurement result of the lower cut-off frequency in Rogowski coil at 0.2Hz shows a significant deviation and could not be reset to zero, which is consistent with the simulation analysis conclusion. It is recommended that the lower cut-off frequency should be lower than 0.1Hz for the external integral Rogowski coil in order to ensure high-precision measurement; fiber-optic current sensor has excellent DC and low-frequency response characteristics, it is an ideal scheme for high-precision measurement of power frequency short-circuit current.
2021 Vol. 42 (10): 1343-1348 [Abstract] ( 249 ) HTML (1 KB)  PDF (2869 KB)  ( 183 )
1349 Design of Null-Detector for DC Resistance Bridge Based on SQUID
ZHANG Peng,YAN Zhi-dan,ZHAO Jian-ting,LU Yun-feng
DOI: 10.3969/j.issn.1000-1158.2021.10.14
A DC resistance bridge null-detector circuit based on superconducting quantum interferometer (SQUID) is designed. The circuit can be used as a null-detector circuit for measuring low and medium value resistance (0.1~100Ω) in high-precision resistance bridges. By making the SQUID peripheral circuit and optimizing the mutual inductance value of its input coupling coil, the precise measurement of unbalanced current of weak bridge is realized. Compared with the traditional resistance bridge based on the nanovoltmeter null-detector measuring unbalance voltage, its detection sensitivity is improved by an order of magnitude in the low-to-medium resistance measurement range. The 1/f corner frequency of SQUID flux locked loop system which is designed as a null-detector, is about 2Hz and the white noise level of the magnetic flux is about 3.5μΦ0/. And the mutual inductance between input coil and SQUID is as high as 10nH, its equivalent current white noise density 0.7pA/. When it is used as a resistance bridge null-detector to measure 100Ω standard resistance (operating current is 10 mA), the resolution can reach the order of 10-11.
2021 Vol. 42 (10): 1349-1353 [Abstract] ( 268 ) HTML (1 KB)  PDF (1345 KB)  ( 421 )
1354 Progress and Prospect of Research on Polarimetric Current Sensor
XU Shao-yi,XUE Hong-yu,XING Fang-fang,ZHANG Shuan,CHEN Guang,PENG Qiang,DONG Feng
DOI: 10.3969/j.issn.1000-1158.2021.10.15
With the continuous development of materials and technologies, the performance and accuracy of plarimetric current sensors have been greatly improved compared to the past. They have been able to meet the actual needs of today's projects. Looking back at the development of polarized fiber current sensors, the key technologies are gradually breakthroughs, such as temperature compensation, suppression of linear birefringence, variable rotation rate fibers, integrated optical waveguide technology, and the production of spun highly birefringence fibers. Based on these new technologies, a new polarimetric current sensor is proposed. The sensor is guided by the single mode fiber. It has a simple structure, high accuracy, and low cost.
2021 Vol. 42 (10): 1354-1366 [Abstract] ( 263 ) HTML (1 KB)  PDF (6313 KB)  ( 669 )
1367 The Loop Antenna Calibration System using the Three-Antenna Method and the Uncertainty Estimation for the Measurement Results
QIN Yao,WU Yan-li,LIU Xiao
DOI: 10.3969/j.issn.1000-1158.2021.10.16
In the 350kHz~30MHz frequency band, in order to accurately obtain the field strength where the loop antenna is located, the antenna factor of the loop antenna needs to be calibrated. The three-antenna method is an absolute method for calibrating the antenna factor.Antenna calibration using the three-antenna method requires three antennas to form three antenna pairs and does not require any reference standard.TAM is discussed in detail, a calibration system based on a vector network analyzer is set up, and the standard uncertainty of the calibration system is evaluated.It is not possible to derive the uncertainty introduced by the calculation formula based on K(i,j). Therefore, the numerical electromagnetics code (NEC) simulations are used to evaluate the uncertainty of K(i,j). The evaluation results show that the extended uncertainty of the four typical frequency points in the 350kHz~30MHz frequency band is less than 0.81dB (k=2).
2021 Vol. 42 (10): 1367-1371 [Abstract] ( 266 ) HTML (1 KB)  PDF (1144 KB)  ( 468 )
1372 Stochastic Resonance Phenomenon of Atangana-Baleanu Fractional Bistable System
WANG Yang-baihui,ZHENG Yong-jun,LUO Zai
DOI: 10.3969/j.issn.1000-1158.2021.10.17
Aiming at the problem of singularity in the study of stochastic resonance based on commonly used fractional calculus, a research method of stochastic resonance in bistable systems based on Atangana-Baleanu fractional calculus is proposed. First, according to the definition of Atangana-Baleanu fractional calculus, the Langevin equation is constructed to describe the stochastic resonance system. Second, it is approximated by the improved Oustaloup algorithm. Finally, simulation program is written to study the effect of parameter changes on stochastic resonance using the single variable control method. The simulation results show that when the noise intensity is constant, by changing the fractional order derivative order, there is a nonlinear relation between the order of fractional derivative and the power spectrum of the output signal and there is an optimal order of fractional derivative to generate stochastic resonance. When the order of fractional derivative is constant, by changing the noise intensity, there is a nonlinear relation between the noise intensity and the power spectrum value of the output signal and there is an optimal noise intensity to generate stochastic resonance.
2021 Vol. 42 (10): 1372-1379 [Abstract] ( 202 ) HTML (1 KB)  PDF (2833 KB)  ( 180 )
1380 The Primary Standard of Neutron Source Strength
ZHANG Hui,GONG Xiao-ming,ZHANG Ya-nan,FAN Cheng
DOI: 10.3969/j.issn.1000-1158.2021.10.18
The manganese bath method is used to absolute measure the neutron emission rate of a radionuclide neutron source, the primary standard can be used to transfer the neutron emission rate. The primary standard is composed of a sphere manganese bath with an inner diameter of 110cm, a gamma measurement system with 2 NaI sensors, a set of solution circulation system and a shielding lead chamber. The modified primary standard participated in the key comparison (BIPM CCRI(III)-K9.Am-Be.1) organized by BIPM, the comparison is equivalent and provided a technical basis for the international recognition of the measurement result of neutron emission rate.
2021 Vol. 42 (10): 1380-1385 [Abstract] ( 240 ) HTML (1 KB)  PDF (938 KB)  ( 163 )
1386 Research on Decomposition of Spectral Overlapping Peaks Based on GMM-ICSA
ZHU Dan-dan,SUN Shi-cheng,YANG Hui,ZHANG Can,ZHU Qi-guang,LI Kang,SHI Yan-xin,CHEN Ying
DOI: 10.3969/j.issn.1000-1158.2021.10.19
Aiming at the difficulties in modeling the element concentration caused by the overlapping peaks of Pb and As in X-ray fluorescence spectroscopy (XRF) and the weak robustness of the crow search algorithm (CSA), the Gaussian mixture model (GMM) is combined with the improved the crow search algorithm (ICSA) to achieve the decomposition of overlapping peaks. Compared with CSA, ICSA has three main improvements: the introduction of the “crow feeding” feature to better connect GMM and ICSA; the fixed probability of awareness is changed to a gradient type to make the population iteration more diverse; appropriate adjustments the global optimization strategy makes the algorithm more stable and converges faster. The comparison experiment between the GMM model and the GMM-ICSA model shows that the decomposition accuracy of the optimized model is increased by 4.93%. At the same time, the mean square error and iteration time are used to measure the quality of the search algorithm, and ICSA is compared with the same type comparative experiments on the four algorithms show that the mean square error and iteration time of ICSA are better than other algorithms, which shows the feasibility of the improved algorithm in dealing with the problem of overlapping peaks.
2021 Vol. 42 (10): 1386-1392 [Abstract] ( 261 ) HTML (1 KB)  PDF (1891 KB)  ( 3583 )
1393 Accurate Measurement of Volume Expansion of Standard Gas Cylinder
WANG De-fa,WU Hai,HUANG Peng,WANG Zhen,WANG Man,LIU Zhi-yong,FENG He-ping,HAN Qiao
DOI: 10.3969/j.issn.1000-1158.2021.10.20
At present, the Gravimetric method is widely used to prepare standard gas. In the process, the uncertainty contribution of air buoyancy introduced by cylinder volume expansion can not be ignored. A device for measuring the gas-filling expansion rate of cylinder is designed. The device can control the pressure of gas filled in cylinder, and measure the volume expansion of cylinder by a precise pipette, so as to accurately calculate the gas-filling expansion rate of cylinder. By using the device, the common 2L, 4L, and 8L aluminum alloy gas cylinders in China are measured. The results show that the expansion volume of cylinder is approximately linearly related to the gas pressure in the cylinder. Moreover, the larger cylinder appearance volume is, the larger gas-filling expansion rate is, and there is a strong correlation between cylinder appearance volume and gas-filling expansion rate. Based on the obtained gas-filling expansion rate data of cylinder, the contribution of cylinder volume expansion to the mass uncertainty of gas filled in cylinder can be further reduced, thus making the calculation of gas mass more accurate.
2021 Vol. 42 (10): 1393-1397 [Abstract] ( 308 ) HTML (1 KB)  PDF (879 KB)  ( 192 )
1398 Study on Efficiency Evaluation and Curve Fitting Optimization of PM2.5 Particle Separation Device Based on Static Chamber Method
LIU Jia-qi,ZHANG Guo-cheng,WU Dan,ZHAO Xiao-ning,JING Wen-jie
DOI: 10.3969/j.issn.1000-1158.2021.10.21
An efficiency evaluation system of PM2.5 particle separation device based on static chamber method was established firstly. In the developed evaluation system, the different aerosol environment conforming to the measurement requirements was generated separately in the static chamber by atomizing 8 kinds of different size polystyrene particle samples. By utilizing an aerodynamic diameter spectrometer, particle concentration before and after particle separation device was measured to obtain the penetration curve of the particle separation device after data fitting. Then, evaluation experiments for a domestic and an imported particle separation devices were carried out to obtain their collecting efficiency. The study is helpful for the production and use of particle separation device, and reference for the subsequent evaluation of other kinds of particle separation devices.
2021 Vol. 42 (10): 1398-1403 [Abstract] ( 212 ) HTML (1 KB)  PDF (862 KB)  ( 418 )
1404 Uncertainty Evaluation for Microbiological Determination of Biotin in Food for Special Medical Use
MENG Jing,WU Yu-jian,ZHONG Li-xia,CHENG Xiang-long,WANG Rui
DOI: 10.3969/j.issn.1000-1158.2021.10.22
The formula food for special medical use is the only source of nutrition for some people, and the accurate quantification of biotin is of great significance. The microbiological method specified in GB 5009.259—2016 was used to determine the content of biotin. The standard uncertainty and expanded uncertainty of biotin were evaluated. The results showed that the content of biotin was (27.16±1.15)μg/100g, p=95%, k=2. The contribution of each component to the uncertainty was analyzed. The results showed that the experimental repeatability was the main influencing factor and the key control point for the determination of biotin by microbiological method.
2021 Vol. 42 (10): 1404-1408 [Abstract] ( 264 ) HTML (1 KB)  PDF (455 KB)  ( 192 )
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