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2023 Vol. 44, No. 12 Published: 2023-12-28

	1783	Parameters Estimation of Newton Rings Based on Fractional Fourier Transform Modified by Triangle Shrinkage Method
		WU Jin-min,JIANG Sheng,LU Ming-feng,SHEN De-ming,FAN Jun-fang,LI Ya-feng,ZHANG Feng,TAO Ran
		DOI: 10.3969/j.issn.1000-1158.2023.12.01
		Aiming at a slower rate when the fractional Fourier transform is used for the estimation of Newton rings parameters, the method based on the triangle shrinkage of the improved fractional Fourier transform is proposed by analyzing the distribution law of the maximum value of the amplitude in the fractional domain of the Newton rings fringe images and the corresponding angle of rotation. The experimental results show that the method is feasible, and the processing time is less than 1s for the fringe images with an image size less than 640×640pixels. With the increase of the image size, the number of fringes contained in the fringe image increases, and the relative error of the estimated value of the radius of curvature decreases. The processing time is still able to meet the practical needs of engineering. When processing the image of 1080×1080pixels, the relative error of the estimated value is 0.001%, and the processing time is 3.31s. The method estimates the 720×720pixels Gaussian noise-damaged Newton ring interferometric fringe image in an average time of 1.28s, which is about 1/700 of the traditional fractional Fourier transform time.
		2023 Vol. 44 (12): 1783-1790 [Abstract] ( 94 ) HTML (1 KB) PDF (671 KB) ( 61 )

	1791	iffraction and Reflection in Terahertz Radiation Spatial Distribution Measurement
		WANG Yuan-cheng,DENG Yu-qiang
		DOI: 10.3969/j.issn.1000-1158.2023.12.02
		To improve the measurement accuracy of terahertz radiation spatial measurement setup, based on the detector scanning sampling setup, the impact factors existing in the terahertz radiation measurement setup are studied by using software simulation and experimental measurement. The concial reflector and terahertz absorption coating are used to reduce the influence of reflection on the measurement results, which can measure the spatial distribution of radiant power density more accurately.On this basis, the law of terahertz diffraction power density distribution with aperture is studied, and the aperture of terahertz transceiver equipment is reasonably optimized, which provides a research reference for the study of high-precision terahertz radiation spatial distribution measurement. Finally, the uncertainty of the beam width is analyzed, and the results show that the reflection in the system after eliminating the influence of reflection has little effect on the test results, the reflection introduction uncertainty is only 1.56%, and the relative standard uncertainty of the measurement system is obtained as 7.6%.
		2023 Vol. 44 (12): 1791-1798 [Abstract] ( 118 ) HTML (1 KB) PDF (929 KB) ( 70 )

	1799	All-fiber Displacement Measurement System Based on Extrinsic F-P Interferometry
		MA Ying-han,ZHANG Shu,PI Lei,YAN Han,HU Jia-cheng,SHI Yu-Shu
		DOI: 10.3969/j.issn.1000-1158.2023.12.03
		In order to solve the problem that the traditional separation mirror group interferometer is too large to be applied in the environment with limited space, all-fiber F-P interferometry displacement measurement technology is studied. According to the interference principle, the influence of different reflectivity conditions on the interference signal form is analyzed. When the reflectivity is 4%, the light intensity signal of multi-beam interference will be approximately a sine function, and the displacement measurement principle is verified by finite element simulation. An all-fiber displacement measurement system based on extrinsic F-P interferometry is designed and built. The experimental results show that the standard deviation of static noise voltage within 1min of the system is 23.3mV, and the linear correlation coefficient R2 of displacement measurement results between the system and commercial XL-80 laser interferometer is 1 within 1mm displacement, and the measurement repeatability of the system is better than that of commercial laser interferometer.
		2023 Vol. 44 (12): 1799-1804 [Abstract] ( 115 ) HTML (1 KB) PDF (611 KB) ( 85 )

	1805	6D Pose Estimation of Sorting Robot Based on Machine Vision
		ZHAO Lan,SHE Yuan,WEN Xiu-lan,LI Guo-cheng,ZHANG Teng-fei,HE Zhong-le
		DOI: 10.3969/j.issn.1000-1158.2023.12.04
		In order to solve the problems of low degree of automation, poor real-time performance and weak portability of traditional sorting robots when they complete designated actions through manual instruction, an experimental platform of sorting robots based on machine vision is designed, and a high-precision 6D pose estimation method based on the mixed progressive registration strategy of coarse registration and enhanced fine registration is proposed. Firstly, the 3D point cloud information collected by the vision sensor is preprocessed, such as background information removal, target region clipping, ROI extraction, etc., and the sampling consistency initial registration algorithm (SAC-IA) is used for pose rough registration. Then the iterative closest point (ICP) algorithm is used for fine registration and the normal distribution transformation (NDT) is used to enhance the fine registration to achieve a high precision 6D position. The experimental results show that the integration of coarse registration and enhanced fine registration can quickly and accurately obtain the 6D position and attitude of the target to be captured, with errors controlled within 1.5mm and 2 ° compared to the theoretical position and attitude, respectively, and meet the practical needs of sorting robots. The proposed method can be applied to the machine vision based robot assembly, grinding and other occasions with high precision 6D pose estimation.
		2023 Vol. 44 (12): 1805-1811 [Abstract] ( 91 ) HTML (1 KB) PDF (716 KB) ( 217 )

	1812	Research on Thickness Measurement of Lubricating Oil Film Based on Contact Resistance Method
		TONG Wei-jie,HUANG Lu,JIA Xin,SUN Miao,CAI Jin-hui
		DOI: 10.3969/j.issn.1000-1158.2023.12.05
		A method for measuring lubricating oil film thickness based on contact resistance method has been proposed, and a rotating friction testing machine that can measure contact resistance in real-time to evaluate lubricating film thickness has been developed. The correlation between oil film thickness and contact resistance in boundary lubrication and mixed lubrication states is studied and established. Load and speed are precisely controlled to realize a stable lubrication condition. The electrical resistance of the contact area is measured in-situ by a specially and precisely designed electrical circuit. Corresponding relation between the contact resistance and lubrication film thickness measured by the optical interference method under the same working conditions has been established,the correlation coefficient of the fitting curve is 0.98, and the remaining standard deviation is 4.56nm. This study provides technical experience and data support for the characterization of lubrication state in real operating conditions.
		2023 Vol. 44 (12): 1812-1818 [Abstract] ( 110 ) HTML (1 KB) PDF (567 KB) ( 115 )

	1819	Two-Phase Flow Pattern Identification Based on Choi-Williams Analysis and Neural Network
		ZHANG Li-feng,ZHANG Si-jia,LIU Shuai
		DOI: 10.3969/j.issn.1000-1158.2023.12.06
		A flow pattern recognition method based on Choi-Williams analysis and neural network is proposed. The array conductivity sensor is used to obtain the flow pattern information of gas-liquid two-phase flow in vertical rising pipeline, and the multivariate measurement data are denoised and dimensionally reduced. Further, Choi-Williams analysis is used to convert it into time-frequency spectrogram, and the data set is constructed. CNN, VGG-16 and ResNet-18 network models are built respectively, and the time-frequency spectrograms of different flow patterns are used as network input for training and testing. The recognition results show that Choi-Williams analysis can effectively extract the characteristics of different flow pattern signals, and the three networks have high recognition accuracy, among which ResNet-18 network has the highest accuracy, with an average flow pattern recognition rate of 99.4%.
		2023 Vol. 44 (12): 1819-1826 [Abstract] ( 76 ) HTML (1 KB) PDF (708 KB) ( 86 )

	1827	Research on Liquid Pressure Transfer Characteristics in Plunger Pressure Generator Based on AMEsim
		TU Yan,ZHU Hai-qing,SHEN Xiao-dong,SHEN Wei,FANG Ming
		DOI: 10.3969/j.issn.1000-1158.2023.12.07
		In order to obtain the relationship between the plunger displacement of the pressure generator and the output pressure, and to achieve the accurate control of the output pressure, the pressure generation system is first modeled mathematically. Then, based on the effective volumetric elastic modulus model of AMEsim, a new interpolation polynomial function of oil gas content is established to solve the derivative mutation problem in the middle position of saturated vapor pressure and air separation pressure. Then, the influence of air content and temperature on the system pressure transfer process is simulated and analyzed. The results show that the system is greatly affected by air content, but less affected by temperature. For every 0.5% increase in air content, the response time and stabilization time of the system will lag about 0.7seconds, and the displacement of the plunger used to compress the oil bubble will increase about 20mm. Finally, by comparing the simulation and measurement results, it is known that the pressure generation system is affected by the air content, the time consumption and response error of the booster section are generally greater than that of the buck section, and the pressure fluctuation of each measuring point is within the range of ±0.03MPa when the pressure is maintained for 5s.
		2023 Vol. 44 (12): 1827-1833 [Abstract] ( 69 ) HTML (1 KB) PDF (635 KB) ( 167 )

	1834	Tool Wear Prediction for Nickel-Based Superalloy Milling
		YANG Li
		DOI: 10.3969/j.issn.1000-1158.2023.12.08
		A new deep learning method based on stacked sparse autoencoders and multi-sensor feature fusion is proposed for milling tool wear prediction by building a nickel-based high temperature alloy milling experimental test platform and analysing tool wear variation patterns. Signal features are extracted in the time domain,frequency domain and time-frequency domain,and the optimal multi-sensor features are determined through correlation analysis,which is input to SSAE for deep feature learning. A tool wear prediction model is established using a bidirectional long-short term memory,and different experimental data sets of milling wear are applied to verify the prediction performance of the trained model. The prediction results show that the root-mean-square error is reduced by at least 9.6% compared to each of the known models, proving that the combination of multi-sensor feature fusion and deep learning methods can improve the prediction performance.
		2023 Vol. 44 (12): 1834-1841 [Abstract] ( 77 ) HTML (1 KB) PDF (749 KB) ( 79 )

	1842	Measurement Errors of Piston Pressure Gauge for Mass Weights and Pressure Weights
		PANG Gui-bing,YANG Yi,FAN Shuang-jiao,YANG Yuan-chao
		DOI: 10.3969/j.issn.1000-1158.2023.12.09
		The types of weights used in existing piston pressure gauges are pressure nominal weights and mass nominal weights,both of which produce different principles of error and lead to different outcome of error. For free distortion pistons,a pressure error model is developed based on the effect of the deformation coefficient on the effective area of the piston,and a general formula for the relative error in pressure generated by using pressure nominal weights and mass nominal weights is derived. Using a piston pressure gauge with a measurement range of 10 to 510MPa as the object of study,error calculations and comparative analyses are carried out to obtain the variation pattern of the pressure errors of the two types of weights. The results show that,under the same conditions,the pressure scale weights produce an additional error of up to -0.0041%within each pressure band due to the repeated use of small,unnumbered weights compared to the mass scale weights.
		2023 Vol. 44 (12): 1842-1846 [Abstract] ( 100 ) HTML (1 KB) PDF (344 KB) ( 45 )

	1847	Research on Inter-beam Interference in ADCP Laboratory Calibration Based on Echo Model Simulation
		LIU Jian-Yao,JIAO Jun-sheng,GUO Shi-xu,ZHANG Ji-wei
		DOI: 10.3969/j.issn.1000-1158.2023.12.10
		Aiming at the problem of low calibration efficiency of acoustic Doppler current profiler (ADCP) in water environment, a simultaneous calibration scheme of multiple beams in laboratory pool environment is proposed. The accuracy of the model is verified by establishing an accurate simulation echo model, and the lake test experiment is carried out to verify the accuracy of the model. The echo model is sent back to the laboratory anechoic tank through the transducer, which can realize the simultaneous calibration of multiple ADCP beams, and use the echo model to explore the interference error between beams during calibration. In the bottom tracking calibration mode, the interference error between beams is positively correlated with the bottom velocity. When the velocity is below 1.6m/s, the relative error is below 0.5%. When it exceeds 1.6m/s, the error exceeds the measurement accuracy of the experimental ADCP. The interference error between beams in the water tracking calibration mode exhibits the characteristics of Gaussian noise, and the relative error is concentrated around 0%. The experimental and simulation results prove the feasibility of the simultaneous calibration scheme of multiple beams in ADCP laboratory, and the error can be controlled within the measurement accuracy range after effective shielding.
		2023 Vol. 44 (12): 1847-1855 [Abstract] ( 82 ) HTML (1 KB) PDF (929 KB) ( 41 )

	1856	Study of Hydrophone Calibration Method Based on Spatial Average Effect Correction
		LU Zong-rui,QIAN Fei-ming,XING Guang-zhen,CHEN Yang,YANG Bo
		DOI: 10.3969/j.issn.1000-1158.2023.12.11
		The hydrophone is a quantitative detection standard in medical ultrasound, and the accurate measurement of its sensitivity is the fundamental for the measurement of sound field parameters and a key link to ensure the safety and effectiveness of ultrasound diagnostic, physical therapy and treatment equipment. In order to solve the problem of increasing sensitivity error caused by the spatial averaging effect of hydrophones, A calibration method based on the spatial averaging effect correction is proposed when using the comparison method to calibrate the hydrophones. Firstly, the sound field is scanned under the pulse wave to obtain the sound beam width at each frequency point, and then the spatially averaged correction model is modeled with the effective diameter of the hydrophone, finally the correction model is introduced. By comparing the experimental results with those before correction, the average relative error is reduced by 4.1% after correction, and the measurement uncertainty is 1.3dB (k=2), and the experimental results verified the effectiveness of the method.
		2023 Vol. 44 (12): 1856-1862 [Abstract] ( 78 ) HTML (1 KB) PDF (499 KB) ( 47 )

	1863	Research on HEV Energy Distribution Strategy Based on Improved Deep Reinforcement Learning
		WU Zhong-qiang,MA Bo-yan
		DOI: 10.3969/j.issn.1000-1158.2023.12.12
		A parallel hybrid vehicle was studied to establish the demand power and power system model of the whole vehicle and proposed an energy distribution strategy based on improved Deep Reinforcement Learning (DRL). The DRB-TD3 algorithm was proposed to improve the sampling efficiency of the original algorithm by improving the Twin Delayed Deep Deterministic Policy Gradient (TD3) algorithm in DRL and introduced dual replay buffers. A rule-based constraint controller was designed and embedded into the algorithm structure to eliminate unreasonable torque allocation. The performance of the Dynamic Planning (DP)-based energy distribution strategy was used as a benchmark for simulation experiment under UDDS driving conditions. The experimental results show that the DRB-TD3 algorithm has the best convergence performance compared with the Deep Deterministic Policy Gradient (DDPG) algorithm and the conventional TD3 algorithm, with 61.2% and 31.6% improvement in convergence efficiency, respectively. The proposed energy distribution strategy reduces the average fuel consumption by 3.3% and 2.3% compared with the DDPG-and TD3-based energy distribution strategies, respectively. The fuel performance reaches 95.2% of DP-based, which with the best fuel economy, and the battery state of charge (SOC) can be maintained at a better level, which helps to extend the battery life.
		2023 Vol. 44 (12): 1863-1871 [Abstract] ( 96 ) HTML (1 KB) PDF (821 KB) ( 136 )

	1872	Research on the Application of Stochastic Resonance in Tri-stable Wells in Weak OFDM Signal Detection
		LIU Gao-hui,PENG Lei
		DOI: 10.3969/j.issn.1000-1158.2023.12.13
		A weak OFDM signal enhancement and demodulation method based on stochastic resonance in tri-stable wells is proposed, and the dynamic characteristics and system performance of stochastic resonance systems in tri-stable wells driven by OFDM baseband complex signals are deeply analyzed. Firstly, the dynamic equation of the stochastic resonance system in the tri-stable well and the mathematical model of the OFDM baseband complex signal are given respectively. Then, the transient response process and the steady-state response process of the stochastic resonance in the tri-stable well are analyzed, and the system from the zero state is deduced. The expression of the transient time required to reach the resonance equilibrium state, the expression of the system output signal when the stochastic resonance system in the trap is in a stable state is derived. In the process of signal enhancement and demodulation, the received OFDM baseband complex signal is firstly segmented according to the symbol period, and the in-phase component and quadrature component signals are simultaneously processed by in-well stochastic resonance, and the simulation is carried out. The simulation results show that the tri-stable stochastic resonance method effectively solves the problem of weak OFDM signal reception performance deterioration under low signal-to-noise ratio, and improves the anti-noise performance of the OFDM system.
		2023 Vol. 44 (12): 1872-1881 [Abstract] ( 73 ) HTML (1 KB) PDF (1105 KB) ( 57 )

	1882	Construction of High Dose Rate 192Ir γ-rays Reference Radiation Field
		ZHI Shi-jie,WANG Ji,WANG Pei-wei,WU Jin-jie,REN Shi-wei
		DOI: 10.3969/j.issn.1000-1158.2023.12.14
		To complete the absolute measurement of the reference air kerma rate of the high dose rate 192Ir radioactive source, a special irradiator and positioning device was designed, and a collimated reference radiation field was built using a medical high dose rate brachytherapy machine. Concerning relevant standards such as ISO 4037, the scattering, radiation field, half-value layer, effective energy and other related parameters of the reference radiation field were measured. The results show that the ambient scattering share is less than 0.003% of the main beam at multiple locations in the radiation field; at a distance of 1.4 m from the radiation source, the diameter of the radiation field is 98 mm, which is larger than the benchmark graphite cavity ionization chamber; the layer measurement result is Cu of 8.224mm,and the effective energy is 402.8keV. The 192Ir energy spectrum measured by HPGe detector is in good agreement with the simulated spectrum. All the parameters met the requirement of the 192Ir brachytherapy source reference air kerma rate to reproduce the magnitude, which laid the foundation for its absolute measurement and international comparison.
		2023 Vol. 44 (12): 1882-1888 [Abstract] ( 88 ) HTML (1 KB) PDF (515 KB) ( 56 )

	1889	Design and Performance Study of the Cavity Ionization Chamber Used in X/γ Radiation Field of 48keV~1.25MeV
		LIU Chuan-feng,CHENG Jian-bo,LI De-hong,CHENG Jin-xing,HUANG Jian-wei,ZHANG Xiao-le,ZHANG Jian,ZHANG Xuan,LI Yue,HAO Guang-hui
		DOI: 10.3969/j.issn.1000-1158.2023.12.15
		The ionization chamber is widely used for the dosimetric measurement on the protection level dose rate in nuclear facilities, radiation therapy, and environmental monitoring. In order to improve the domestic manufacturing level of the ionization chamber, the cavity ionization chamber was studied. The thickness of the ionization chamber wall and the design of the guard electrode were studied by the method of theoretical analysis and Monte Carlo simulation. The designed cavity ionization chamber was tested in the standard X and γ radiation field to evaluate the dosimetry characteristic. The results showed that the leakage current was less than ±5fA, and the work voltage of the cavity ionization chamber was 200~800V. The energy response was tested in the N60~N250 X radiation field and the 137Cs, 60Co γ radiation filed. When the dose rate is normalized to 60Co radiation field, the energy response was better than ±5%. The long-term stability and the angular response of the ionization chamber in half a year was better than 0.5%. At last, it can realize the measurement of dose rate of 3mGy/h~30Gy/h with the relative deviation for the agreed dose rate better than ±5%.
		2023 Vol. 44 (12): 1889-1896 [Abstract] ( 98 ) HTML (1 KB) PDF (498 KB) ( 46 )

	1897	Measurements of Absorbed Dose to Water in Medical Electron Beams and Discussion of Its Uncertainty
		WANG Zhi-peng,WANG Kun,JIN Sun-jun,YANG Xiao-yuan,QI Ya-ping,HUANG Ji,LIU Fu-bin
		DOI: 10.3969/j.issn.1000-1158.2023.12.16
		The measurement uncertainty of absorbed dose to water, Dw, in medical electron beams exceeds 3%, which is difficult to meet the requirements of clinical treatment and verification regulation of medical electron accelerator radiation source. The research on measuring electron beam radiation dosimetry using water calorimetry was carried out by the National Institute of Metrology (NIM), which realized the direct measurement of the Dw, with a relative standard uncertainty of 0.35%. At the same time, the research on the homogenous traceability of medical electron beams have also been carried out. Five schemes for measuring the absorbed dose to water in electron beams have been summarized. The relative standard uncertainty includes the highest 3.7% and the lowest 1.4%. In order to facilitate the measurement of the Dw in clinical electron beams, some suggestions on the selection and calibration methods of ionization chambers were provided, and precautions for different calibration coefficients were emphasized.
		2023 Vol. 44 (12): 1897-1903 [Abstract] ( 88 ) HTML (1 KB) PDF (364 KB) ( 61 )

	1904	Measurement and Uncertainty Evaluation of Fullerene Purity Based on Ultraviolet-visible Spectrophotometer
		ZHAO Chun-yue,RENG Ling-ling,PU Cheng,SHAO Hong-fei,YAO Ya-xuan
		DOI: 10.3969/j.issn.1000-1158.2023.12.17
		The purity has an impact on fullerene’s mechanical, thermal and other properties of fullerene, hence its applications in lubricity, superconductivity and other related areas. Ultraviolet-visible (UV-vis) spectrophotometer is a simple and convenient technique for rapid determination of fullerene purity. Yet, elaborated systematic analysis on measurement influencing factors are currently not been reported. Based on UV-vis spectrophotometer, a mathematical model for purity determination of C60 was established, and uncertainty was evaluated by analyzing all possible uncertainty sources. The results showed that the purity of C60 prepared by arc method is (74±7)%, k=2; and the purity of C60 prepared by combustion method is (99±9)%, k=2. Based on uncertainty evaluation, main sources of uncertainty come from linear fitting of standard curve and preparation of standard series solutions, which may provide technical basis for optimization of measurement conditions with reduced uncertainty and improved accuracy for future study.
		2023 Vol. 44 (12): 1904-1911 [Abstract] ( 83 ) HTML (1 KB) PDF (468 KB) ( 70 )

	1912	Development of Total Residual Chlorine Reference Material
		GONG Wei,YAO Xu-xia,TIAN Ping,Lü Hui,LIU Xin
		DOI: 10.3969/j.issn.1000-1158.2023.12.18
		Residual chlorine is an important indicator for water quality monitoring and an important parameter for judging water quality.For this reason, the national second-class total residual chlorine reference materials GBW(E)084725, GBW(E)084726 were developed. According to the commonly used measurement methods of total residual chlorine, the method suitable for the calibration of reference materials was selected, and the methodology of the calibration method was studied. The homogeneity and stability of total residual chlorine reference materials with two concentrations were tested respectively. The F value of variance test was less than the critical value, indicating that the homogeneity of the reference material was good. During the six month stability investigation period, there was no statistically significant change in the reference materials with two contents. At the same time, ten day short-term high and low temperature simulation experiments were conducted. The results showed that there was no significant change statistically in the reference materials with two contents either, which indicated the stability of the two reference materials was good. The redox titration method was used for the determination of reference materials. The quantity values were 50mg/L and 500mg/L respectively, and the relative expanded uncertainty was 0.9% and 0.5% (k=2) respectively.
		2023 Vol. 44 (12): 1912-1918 [Abstract] ( 77 ) HTML (1 KB) PDF (460 KB) ( 50 )

	1919	Development of Quantum Dot-Doped Fluorescent Gel Reference Strip and Its Application in Calibration of Fluorescence Immunoassay Analyzer
		TAO Qing,WANG Le-le,PENG Tao,LI Lan-ying,LIU Gang,WEN Yan-li
		DOI: 10.3969/j.issn.1000-1158.2023.12.19
		Quantum dot-doped fluorescent gel reference strips were developed based on microfluidics and quantum dot technology. These strips were formed by uniformly mixed quantum dots and PDMS, which were pressed into capillary tubes to solidify. By controlling the concentration of quantum dots, fluorescent gel reference strips with three fluorescence intensities of high, medium, and low were prepared. The photobleaching, homogeneity, and stability of the reference strips were investigated, and the uncertainties were evaluated. The results showed that the fluorescent gel reference strips possessed good photobleaching resistance and uniformity, and can be stored stably for 180 days at room temperature in the dark. Calibration experiments on a number of fluorescent immunoassay analyzers proved that the fluorescent gel reference strips had good applicability and provided a reliable reference for the calibration of fluorescent immunoassay analyzers.
		2023 Vol. 44 (12): 1919-1924 [Abstract] ( 92 ) HTML (1 KB) PDF (521 KB) ( 93 )

	1925	Influencing Factors Analysis in Quantitative Evaluation of Andersen Six-level Impact Microbial Sampler
		LIU Jia-qi,ZHANG Guo-cheng,TIAN Ying,WU Dan,SHEN Shang-yi,LI Bo-ya,HUO Sheng-wei
		DOI: 10.3969/j.issn.1000-1158.2023.12.20
		Due to the lack of standards and detection technical specifications for Andersen six-level impact microbial samplers, an evaluation method based on the capture efficiency curve for the aerodynamic particle size at a sampling physical efficiency of 50% (Da50) was proposed, and the detection and theoretical calculation of Da50 as well as its influencing factors were analyzed. Five domestic brands of Andersen samplers were tested, and it was found that the measurement results of different manufacturers' products varied significantly, the first or multi-level capture efficiency curves of multiple products corresponded to Da50 outside the particle size range. Research has found that the difference in sampler performance is not caused by insufficient aperture processing accuracy. The research results indicate that the higher the culture medium, the smaller the obtained Da50, under the same height of the culture medium, the ideal distance between layers is about 10mm. Therefore, the impact height is an important factor affecting the performance of Andersen six-level impact microbial samplers.
		2023 Vol. 44 (12): 1925-1931 [Abstract] ( 71 ) HTML (1 KB) PDF (521 KB) ( 41 )

	1932	Improved Grey Evaluation Method for Uncertainty of Minimum Sample Data
		ZHU Yan-long,CHENG Yin-bao,GAO Hong-tang,WANG Yan,SHI Jiang-huan,LUO Zai,LI Ya-ru
		DOI: 10.3969/j.issn.1000-1158.2023.12.21
		In order to solve the limitation problem of the classical grey assessment model of measurement uncertainty under the condition of very small sample, SMOTE technique and SVR model are introduced on the basis of analyzing the principle of the classical model. Then, an improved grey evaluation method of measurement uncertainty is proposed after applicability modification. Finally, the computer simulation data and the total temperature data from the air flow measurement of an aero-engine high-altitude simulation experiment are applied to the model to verify the reliability and generalization of the model. The results show that the improved grey method can adapt to the minimum sample size data of different distribution types with the calculation results of the range method as a reference. The maximum improvement is 41.18% in the simulation data and 50.00% in the instance data.Therefore, this improved grey method may be an effective way to solve the uncertainty evaluation of very small sample data.
		2023 Vol. 44 (12): 1932-1938 [Abstract] ( 103 ) HTML (1 KB) PDF (489 KB) ( 60 )

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