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2022 Vol. 43, No. 4 Published: 2022-04-28

	437	Uncertainty Evaluation on Displacement of Blocking Electrodes in Calculable Capacitor
		WANG Jian-bo,YIN Cong,QIAN Jin,LIU Zhong-you,HUANG Lu,YANG Yan,LU Zu-liang
		DOI: 10.3969/j.issn.1000-1158.2022.04.01
		The calculable capacitor is a classical and fundamental experiment apparatus in precise electromagnetic measurements. It is followed the ‘new’ electromagnetic principle which is firstly introduced by Lampard D G and Thompson A E. The calculable capacitor is the AC impedance primary standard, and its the traceable source of the capacitance, inductance and AC impedance. It is a high-accuracy (at the level of 10-8) apparatus surpassed only by the quantum Josephson voltage and quantum Hall resistance experiments in the electromagnetic metrological field, and it is expected to reach the level of 10-9 through continual improvements and optimizations to improve the uncertainty level of electromagnetic metrology. The basic principle of the displacement measurement in calculable capacitor is presented, and impact factors, including Fabry-Perot interferometer locking, laser wavelength, residual index of refraction of air, cosine error and Gouy phase correction, are analyzed. Combining the repeatability of capacitance produced by calculable capacitor, a relative standard uncertainty of 4.7×10^-9 is obtained.
		2022 Vol. 43 (4): 437-444 [Abstract] ( 313 ) HTML (1 KB) PDF (3126 KB) ( 511 )

	445	Direct Measurement Method of Planck Constant Based on Photon Energy Measurement
		LI Yu-fen,HE Sui-rong,WEI Lian-fu
		DOI: 10.3969/j.issn.1000-1158.2022.04.02
		Planck’s constant is the smallest acting quantum in physics. It is a mark to distinguish classical physics from quantum phenomena. Therefore, the accurate measurement of such a basic physical constant is very important, not only to understand the origin of the material world, the experimental observation of various quantum effects, but also for the establishment of the physical measurement benchmark of mass units. The precise measurements of Planck constant have demonstrated for more than 120 years, by various indirect and direct methods. Although its exact value was given in 2019, the accuracy of its measurement value is still not enough, specifically compared to that of the time and frequency measurements. As a new development of the indirect measurement of Plancks constant by the traditional photoelectric effect method, a direct measurement method of Plancks constant is proposed by using the photon-induced ionization of electrons on liquid helium. The saturated photocurrent platforms could be measured by using the photon number resolution detectors for the different intensity lasers. The feasibility of the method could be achieved by using the existing micro/nano technique to fabricate the devices, which will be measured in a low temperature weak signal detection system.
		2022 Vol. 43 (4): 445-451 [Abstract] ( 197 ) HTML (1 KB) PDF (1922 KB) ( 471 )

	452	Error Measurement and Modeling Compensation of Three Axis Perpendicularity of Micro-nano CMM
		LI Rui-jun,LI Jie,HE Ya-xiong,CHENG Zhen-ying,HUANG Qiang-xian
		DOI: 10.3969/j.issn.1000-1158.2022.04.03
		The perpendicularity error is one of an important error sources of micro-nano coordinate measuring machines (CMMs). This error should be measured with high accuracy and compensated by an effective model. The measurement setup based on PSD was used to measure the straightness errors which can be transformed into the perpendicularity errors of the micro-nano CMM. A model for perpendicularity errors of the micro-nano CMM was built and used to compensate the errors. Several 0-class gauge blocks were measured and the measuring errors in X and Y directions of the blocks were reduced by 11μm and 5μm respectively after the compensation. The correctness of the perpendicularity error measuring method and the effectiveness of the compensation model were validated.
		2022 Vol. 43 (4): 452-456 [Abstract] ( 242 ) HTML (1 KB) PDF (1539 KB) ( 495 )

	457	Research on Vision Calibration Method of the Pitch Axis Position
		BI Chao,ZHAO Yuan,HAO Xue,FANG Jian-guo
		DOI: 10.3969/j.issn.1000-1158.2022.04.04
		With regard to the calibration difficulty of pitch axis positions in the five-axis vision measuring system for film cooling holes, a new calibration method based on industrial camera and specially designed target was proposed. During the implementation of the method, a cuboid metal block with sharp and intact edges was applied as the calibration target. In the calibrating procedure, the target was placed at different positions and postures by the rotations of the pitch axis. Afterwards, the industrial camera focused on the surfaces of the target in different situations and then captured the images of the same goal edge on the front surface and upper surface respectively. According to the constraint condition established by the uniqueness of the goal edge extracted from those images, spatial position of the pitch axis in the measuring space denoted by O-XYZ would be calculated by solving simultaneous equations. At last, to verify the calibration method and results, a test piece was measured 10 times by the system after pitch axis position calibration, whose nominal size was 60mm. As shown in the inspecting experiments, the limit errors of single measurement of the length dimension were ±0.0216mm, and the measuring errors of those experimental results were all smaller than ±0.012mm, which manifested the feasibility and effectiveness of the calibration method proposed.
		2022 Vol. 43 (4): 457-463 [Abstract] ( 200 ) HTML (1 KB) PDF (2651 KB) ( 271 )

	464	Reproducible and Accurate Fabrication of High Gain Raman Gold Plated Tips Based on FDTD Simulation
		ZHU Min-hao,GAO Si-tian,HUANG Lu,HU Jia-cheng,SUN Xiao-shuang,LIU Lin-wei
		DOI: 10.3969/j.issn.1000-1158.2022.04.05
		A high gain Raman tip suitable for tip enhanced Raman system (TERS) based on finite difference time domain (FDTD) simulation and its preparation methods are put forward. The near-field electric field distribution of the concave tungsten tip with gold plating thickness of (5～100)nm and with intermediate transition layer materials of 5nm concluding SiO2, Ta2O5, Ti, Cu is simulated and analyzed at the gold hemispherical sample on the gold substrate. The simulation results show that the tip with a gold plating thickness of 50nm and intermediate interlayer of Ti and Cu have the strongest enhancement effect. On this basis, the designed high-gain tip was successfully prepared by magnetron sputtering and the titanium plating time was set at 7s and 120s for gold plating. The tip was cut by focusing ion beam (FIB) and the profile structure of the tip was observed by a scanning electron microscope (SEM), and the size and shape of the coated tip were verified to meet the design requirements. After 4 batches of 20 needles in each batch, repeated coating experiments were carried out, which proved that the designed needles were stable and could be prepared repeatedly.
		2022 Vol. 43 (4): 464-469 [Abstract] ( 221 ) HTML (1 KB) PDF (2345 KB) ( 130 )

	470	Multi-target Tracking Algorithm Based on ReInspect Algorithm
		WANG Wen-yuan,JIN Xuan-hong,SONG Wen-jing,WANG Yi-wei
		DOI: 10.3969/j.issn.1000-1158.2022.04.06
		In order to improve the accuracy of multi-target detection in complex scenes,a detection method for multiple moving objects based on ReInspect algorithm is proposed. The algorithm is based on the OverFeat algorithm and Faster R-CNN algorithm, adding LSTM (long short-term memory)recurrent network structure to record the feature sequence of multiple targets. By adjusting the LSTM network feature label information to preprocess the loss function, and the confidence segmentation method is used after tracking to match the detection results to solve the problem of repeated detection of the same target and target occlusion. The experimental results show that the algorithm has good anti-interference ability against traditional overlapping and occlusion problems, and the recognition accuracy is higher than 90% in different scenarios.
		2022 Vol. 43 (4): 470-474 [Abstract] ( 242 ) HTML (1 KB) PDF (2147 KB) ( 292 )

	475	Dynamic Glare Measurement Method Based on Threshold Increment
		WANG Jia-ming,QIAO Wei-dong,ZHANG Heng,LI Yi
		DOI: 10.3969/j.issn.1000-1158.2022.04.07
		By analyzing the evaluation criteria of threshold increment, it is concluded that the basic components affecting the change are brightness information and position information. A dynamic glare measurement method based on threshold increment is proposed, and an experimental measurement system is established. The system uses image collector to obtain environmental image information, obtains image brightness information and three-dimensional coordinate information through image brightness calibration method and binocular camera visual characteristics, and realizes the calculation of single frame image threshold increment. Finally, the detection frequency of the system is estimated according to the system operation time, and the estimated frequency is verified in practice. The experimental results show that the detection frequency of the dynamic glare measurement system can reach 7.67Hz. Compared with the traditional detection methods, this method has the characteristics of high efficiency, dynamic and intelligent, and can meet the actual needs of threshold increment measurement in dynamic scenes.
		2022 Vol. 43 (4): 475-481 [Abstract] ( 192 ) HTML (1 KB) PDF (1390 KB) ( 186 )

	482	Study on Dynamic Threshold Method Based on Echo Similarity for Ultrasonic Gas Flow Meter
		MA Ye-chi,ZHAO Wei-guo,ZHANG Sheng-yi
		DOI: 10.3969/j.issn.1000-1158.2022.04.08
		The first threshold detection and zero crossing detection are often used to determine arrival point of echo signal in the gas ultrasonic flow meter based on double threshold method.However,the echo wave is easily distorted caused by environment change,which lead to the first threshold wrong setting.As a result,the arrival point of echo will be shifted to the wrong position and the measurement accuracy will be affected.Therefore,a dynamic threshold method based on echo similarity is proposed.The several maximum amplitude of echo signal are obtained,the Euclidean distance of the rising area of the echo signal are calculated to evaluate the similarity.Then the threshold voltage is determined according to the maximum similarity to realize the dynamic threshold value.The correct threshold setting ensures that the accurate positioning of echo signal arrival time point.So the accurate measurement of flight time is obtained.Finally,the experimental results show that the method has good applicability under different working conditions.The measurement error of the prototype is better than 1% and the repeatability is better than 0.2%.
		2022 Vol. 43 (4): 482-488 [Abstract] ( 208 ) HTML (1 KB) PDF (3877 KB) ( 224 )

	489	Design of Host System for Miniature Absolute Gravimeter
		XU Jin-yi,SU Duo-wu,WANG Qi-yu,JI Wang-xi,FENG Jin-yang,LI Chun-jian,WU Shu-qing,HU Ruo
		DOI: 10.3969/j.issn.1000-1158.2022.04.09
		To solve the problem that the operation mode of the drive tray of NIM-3A and NIM-3C absolute gravimeters arise self-vibration and the influence of magnetic materials on the accuracy and stability of gravity measurement when they are used on vehicle or common base, a miniature absolute gravimeter host system is designed. The influence of self-vibration and magnetic materials was avoided by changing the previous servo tracking motion of the driving tray to a novel tray driving mode that measures the falling body with no other internal mechanical motion due to the first falling of the tray. In the situation of reducing the weight of the host system to 30kg, the measurement speed can be increased from 3 times/min for NIM-3A to 6 times/min, and the estimated measurement uncertainty decreased from 30μGal in the previous NIM-3C gravimeter to 10μGal.
		2022 Vol. 43 (4): 489-493 [Abstract] ( 157 ) HTML (1 KB) PDF (1420 KB) ( 178 )

	494	Research on High Precision Quantitative Packing Equipment for Salt and Its Kinds
		WANG Jia-en,NIE Xiao-gen
		DOI: 10.3969/j.issn.1000-1158.2022.04.10
		Aiming at the problems of low weighing precision and low automation in salt quantitative packing production, the high precision salt quantitative packing equipment was studied. The weighing device was designed as adjustable measuring cup structure to estimate the salt quality by measuring cup volume, and the re-inspection feedback device was designed as multi-sensor belt weighing structure to overcome the influence of the weight ratio of dead-weight to salt weight on the weighing precision. Analyzing the errors in the dynamic weighing process, the closed-loop optimized quantitative packing control system was designed based on iterative learning and fuzzy algorithm. Through on-line operation experiments, the results indicate that the system can achieve high precision quantitative packing for salt, which has the ability of anti-disturbance and adaptation. After 3~4 times of iterative learning compensation control, the precision requirement whose allowable shortage of quantitative packing is 3% can be reached stably under the working environment of less than 50% error change rate.
		2022 Vol. 43 (4): 494-500 [Abstract] ( 159 ) HTML (1 KB) PDF (2073 KB) ( 105 )

	501	Tool Wear Monitoring Method Based on One-Dimensional Residual Network with Threshold Module
		GUO Bao-su,HAN Tian-jie,ZHANG Yu,WU Feng-he
		DOI: 10.3969/j.issn.1000-1158.2022.04.11
		A tool wear monitoring model based on one-dimensional residual network with threshold module and a tool wear prediction model based on bidirectional long short-term memory network are designed. The sensor signal is input into the monitoring model after wavelet decomposition, the threshold module automatically selects the threshold to reduce the noise of the signal and the residual module extracts the signal characteristics, then outputs the tool wear monitoring value, and inputs it into the prediction model to obtain the tool wear prediction value. The experimental results show that the monitoring accuracy of this monitoring model is improved by 0.327% and 1.697% respectively compared with the one-dimensional residual network model without threshold module and convolution neural network model; the prediction effect of the prediction model is good, and the absolute error is only 0.024.
		2022 Vol. 43 (4): 501-506 [Abstract] ( 187 ) HTML (1 KB) PDF (2799 KB) ( 444 )

	507	Research on Metrological Performance of 10kPa Pneumatic Piston Gauge
		YUE Jin,YANG Yuan-chao
		DOI: 10.3969/j.issn.1000-1158.2022.04.12
		To measure the effective area and discrimination threshold of a 1.2~10kPa pneumatic piston gauge,the FPG8601-type piston gauge (FPG) was used as the standard.The characteristics and traceability methods of the FPG8601-type piston gauge are introduced.The necessity of full-range measurement of pneumatic piston gauge and measurement procedure are expounded.The measurements were carried out at five different pressure including the lower limit of pneumatic piston gauge,and the average effective area of the piston-cylinder is 9.77371cm² .By changing different small weights on the piston of pneumatic piston gauge and reading the corresponding pressure value of the FPG8601-type piston gauge,the discrimination threshold of pneumatic piston gauge was measured.The discrimination threshold is better than 5mg which is better than 2×10^-5 compared with the measurement point.The uncertainty of the effective area at each point was evaluated,and the results show that the relative expanded uncertainty does not exceed 9.4×10^-5.
		2022 Vol. 43 (4): 507-512 [Abstract] ( 211 ) HTML (1 KB) PDF (1962 KB) ( 251 )

	513	Hysteresis Modeling and Parameter Identification of GMM-FBG Current Sensor Based on Dynamic Free Energy Hysteresis Model
		TENG Feng-cheng,YANG Xue-fan,Lü Deng-yan,YE Wen-hao
		DOI: 10.3969/j.issn.1000-1158.2022.04.13
		In order to solve the hysteresis nonlinearity and eddy current loss problems in GMM-FBG current sensor, a dynamic free energy hysteresis model of coupled eddy current loss model was proposed, and nonlinear genetic algorithm was used to identify and optimize the parameters of the model, which improved the prediction accuracy of the model to the hysteresis curve at power frequency. A GMM-FBG current sensor experimental platform was built, and the hysteresis model was used to compensate the sensor system and verify the sensor system. The experimental results showed that the model can well predict the dynamic hysteresis nonlinearity of the sensor under power frequency, the prediction error of the model is within 3.6%, and the sensitivity of current measurement can reach 0.069nm/A.
		2022 Vol. 43 (4): 513-520 [Abstract] ( 188 ) HTML (1 KB) PDF (1838 KB) ( 165 )

	521	Research on Nonlinear Mechanish of DC Resistive Voltage Divider
		WANG Chu,ZHANG Li-li,ZHANG Guo-shuai
		DOI: 10.3969/j.issn.1000-1158.2022.04.14
		Aiming at the nonlinear phenomenon of the resistive voltage divider in the DC low voltage division. The independent influencing factors analysis method is used to study the nonlinear mechanism of the DC resistive voltage divider. Through analysis and experimental verification, make sure that the output thermoelectric potential of the resistive voltage divider changes with the working current, lead to the non-linear divider ratio. According to the above study, the nonlinear mathematical model is founded, and proposing the nonlinear correction method. Using the mentioned method, the maximum non-linear deviation of ±200μV DC voltage output is less than 5nV.
		2022 Vol. 43 (4): 521-525 [Abstract] ( 226 ) HTML (1 KB) PDF (773 KB) ( 175 )

	526	The Influence of Measurement Condition to the Effective Bits Evaluation of A/D in Sine-Fit Method
		LIANG Zhi-guo
		DOI: 10.3969/j.issn.1000-1158.2022.04.15
		Aiming at the influence of measurement conditions on the error of the effective bits of A/D converters by the sine fitting method, a study of the fitting error bounds is carried out. The selected condition variables are the A/D bits number, the signals amplitude, the number of signal cycles in sampling sequence, the initial phase, the DC bias, and the number of data points in sampling sequence. The error bounds search is carried out in the dual condition combination method, and the error of dynamic effective bits evaluation via the changes of different conditions is obtained, both the significant influence and the insignificant influence are screened out. Through the study of the influence of the number of A/D bits, the number of signals cycles in sequence, and the number of data points, and the significant law that the error boundary showing the characteristics of the quantization step has been obtained, and the estimation of the boundary point of the quantization step has been obtained by empirical formula. The result can be used to estimate the evaluation error and uncertainty of the dynamic effective bits, and can also be used to select the measurement conditions under the condition of setting the fitting error and uncertainty.
		2022 Vol. 43 (4): 526-535 [Abstract] ( 196 ) HTML (1 KB) PDF (4979 KB) ( 114 )

	536	An Optimized Weighting Method for Atomic Clock Ensemble
		YU Hang,ZHANG Lei,SONG Wen-xia,WANG Yu-zhuo
		DOI: 10.3969/j.issn.1000-1158.2022.04.16
		Atomic clock group integration technology is widely used in time keeping systems to maintain the accuracy, stability and continuity of time scale. However, there is always a certain correlation between atomic clocks in the same laboratory, which limits the performance of atomic time scales. Based on the correlation between the atomic clock ensemble and its covariance matrix, this paper investigates the influence of same environmental factors on the frequency characteristics of atomic clock. A new weighting method for atomic clock ensemble is designed with optimization theory. It was applied to the cesium clock ensemble at NIM. The results showed the new method could reduce greatly the frequency instability of the clock ensemble.
		2022 Vol. 43 (4): 536-541 [Abstract] ( 224 ) HTML (1 KB) PDF (2118 KB) ( 125 )

	542	Real-time Disciplining of Rubidium Clock for Remote Time Traceability with Two Way Optical Fiber Time and Frequency Transfer
		FANG Wei,JIN Shang-zhong,CHEN De-hao,LIANG Kun
		DOI: 10.3969/j.issn.1000-1158.2022.04.17
		To improve the remote time traceability performance of the rubidium atomic clock, the high-precision quasi-real-time disciplining experiments were implemented on the rubidium atomic clock based on the TWOTFT links of National Institute of Metrology (NIM). In the experiment, the disciplining intervals are 16min, 5min, and 1min, which realizes the verification of the principle of remote time traceability based on TWOTFT. The experimental results show that in remote time traceability, TWOTFT is more effective than GNSS time-frequency transfer, and the remote time traceability effect with a disciplining interval of 1 minute is the best, and 98.67% of the absolute values of the time differences are within 0.5ns, and the time stability and frequency stability are 2.5×10^-11s·d^-1 and 5.0×10^-16d^-1 respectively.
		2022 Vol. 43 (4): 542-546 [Abstract] ( 227 ) HTML (1 KB) PDF (2181 KB) ( 455 )

	547	Study on Modified CGGTTS Algorithm Based on Real-time Performance and Data Utilization Rate
		HAO Shuang-yu,BI Hong-jun,LIANG Kun
		DOI: 10.3969/j.issn.1000-1158.2022.04.18
		To avoid waste of measurement data, the GNSS time-frequency transfer data standard format CGGTTS has been improved. The improvement mainly includes: using all the measurement data in the data period to calculate the time difference values to improve the utilization rate of the measurement data. At the same time, in order to meet the higher requirements of time transfer users for real-time data, the CGGTTS data period is shortened to improve the performance of real-time. The experimental results show that when the data usage rate is increased to 100%, the noise of the comparison results can be reduced, and the noise performance can be improved by up to 6%. After shortening the data interval to 5 minutes, the real-time performance of the data is increased to 69%, and the noise performance deteriorates by more than 17%. Analyze the real-time performance, standard deviation, data volume, and calculation volume of files at different intervals, and it is obtained that when the data interval is between 8 and 13 minutes, the improved CGGTTS algorithm keeps the noise level of the common clock difference experiments at (0.70～0.80)ns, and the noise level of the long baseline experiments at (0.75～0.83)ns, which is a compromise choice.
		2022 Vol. 43 (4): 547-553 [Abstract] ( 267 ) HTML (1 KB) PDF (4031 KB) ( 250 )

	554	Study on Radiation Characteristics and Energy Compensation of GM Tube
		XU Yang,GAO Fei,ZHAO Rui,NI Ning, HUANG Shao-peng,WANG Fei-fei,LIN Min
		DOI: 10.3969/j.issn.1000-1158.2022.04.19
		Based on the X and γ-ray reference radiation field of the primary metering station of ionizing radiation of Defense Science & Technology Industry, the radiation characteristics of j613r type GM tube produced by a manufacturer were experimentally studied. Combined with the CT imaging system of the National Institute of Metrology, the internal structure size of the tube was accurately measured, and the energy compensation for the sensitive area was carried out. The results showed that the tube can be used for dose determination in the range of 10.62μSv/h～161.52mSv/h. The optimal compensation area of sensitive region is 88%～90% with the central slit is opened, and 0.81mm Pb compensation layer is applied. After compensation, the deviation of 137Cs is within ±20% in the range of 48～662keV, which can provide measurement components for personal dosimeter.
		2022 Vol. 43 (4): 554-559 [Abstract] ( 276 ) HTML (1 KB) PDF (1851 KB) ( 136 )

	560	Uncertainty Evaluation for the Furfural Content in Transformer Oil by HPLC
		ZHANG Lin-ying,HE Shi-zhong,QIU Hui-rao,ZHANG Jing-ru
		DOI: 10.3969/j.issn.1000-1158.2022.04.20
		Furfural content in transformer oil can evaluate the aging condition of transformer insulating paper and reflect its insulation performance. Through the quantitative analysis of furfural content in transformer oil by high performance liquid chromatography, the mathematical model was established. It was determined that the uncertainty sources of the determination results are furfural reference material, preparation of standard oil, fitting of standard curve, sample preparation, recovery and measurement repeatability, and the uncertainty of the test results was evaluated. The experimental results showed that the concentration of furfural in the electric insulating oil is 1.05mg/kg, and its extended uncertainty U95=0.03mg/kg, the fitting of standard curve is the main source of uncertainty in the determination of furfural by HPLC.
		2022 Vol. 43 (4): 560-564 [Abstract] ( 242 ) HTML (1 KB) PDF (473 KB) ( 242 )

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