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2020 Vol. 41, No. 11 Published: 2020-11-28

	1313	Modeling and Analysis of Sequential Multi-lateration Measurement System Based on Single Laser Tracker for Robot Calibration
		QIAO Gui-fang,SUN Da-lin,WEN Xiu-lan,SONG Guang-ming,ZHANG Ying,SONG Ai-guo
		DOI: 10.3969/j.issn.1000-1158.2020.11.01
		To implement the accurate calibration of large serial industrial robot, a sequential multi-lateration measurement system of single laser tracker is presented. The system only needs single laser tracker to measure the end position of industrial robots in different base stations. The end position of robots is calculated based on the multilateral measurement method. Due to the distance data needed in the calculation, the measurement uncertainty of position can be effectively reduced. Firstly, the simulation model of the measurement system is established. The influence of the number of the measuring points, the distribution shape, the measuring distance and the positioning accuracy of industrial robots on the measuring accuracy of the proposed system is intensively studied. Secondly, according to the analysis results, the construction scheme of the sequential multi-station measurement system based on single laser tracker is determined. The experimental results show that the measurement error of the system is only 0.023mm at 2.5m distance, which is better than the accuracy of laser tracker. It can satisfy the measurement accuracy requirement of parameters calibration of the large serial industrial robot.
		2020 Vol. 41 (11): 1313-1320 [Abstract] ( 310 ) HTML (1 KB) PDF (2226 KB) ( 294 )

	1321	Design and Experimental Verification of Positioning Platform for Double-probe Atomic Force Microscopy
		LIN Zhi-dong,GAO Si-tian,HUANG Lu,LI Qi
		DOI: 10.3969/j.issn.1000-1158.2020.11.02
		A large-stroke positioning platform that provides precise displacement is designed for the needs of dual-probe atomic force microscopy. A flexible hinge and a piezoelectric actuator are respectively used as a guiding mechanism and a driving mechanism of the positioning platform. The X,Y,and Z axis motion directions are independently displaced by a parallel mechanism. Mathematical modeling of the positioning platform,analysis and calculation of the working stiffness and natural frequency of the positioning platform,and finite element simulation analysis. Mathematical modeling of the positioning platform is carried out, the working stiffness and natural frequency of the positioning platform are analyzed and calculated, and the finite element simulation analysis is carried out. The experimental devices of the positioning platform are constructed with the capacitive sensor as the displacement measuring unit,and the experimental verification is carried out. Experimental results show that the positioning platform has a travel distance of 110μm in the X and Y axis directions with a resolution of 5nm,and a travel distance of 45μm in the Z axis direction with a resolution of 5nm.
		2020 Vol. 41 (11): 1321-1326 [Abstract] ( 322 ) HTML (1 KB) PDF (1828 KB) ( 284 )

	1327	An evaluation method for thick oil film on sea surface based on band ratio method
		CUI Yong-qiang,KONG De-ming,KONG Ling-fu,ZHANG Xiao-dan,KONG De-han,YUAN Li,LI Chao
		DOI: 10.3969/j.issn.1000-1158.2020.11.03
		Oil spill has become one of the most serious problems of marine pollution, laser-induced fluorescence (LIF) technology is considered to be one of the most effective detection technologies for sea oil spill. At present, based on LIF, the oil film thickness inversion algorithm is only suitable for the thin oil film (≤20μm). In order to detect the thick oil film, a dual-band ratio model is proposed to evaluate the thickness of thick oil film, the wave characteristics of oil film fluorescence spectra are used to invert the thickness and the applicability of the method are given. The method is verified by experiments. When the oil film is thin, the inversion error is large, and it decreases gradually with the increase of the oil film thickness. When the oil film fluorescence signal tends to saturation, the inversion error is large and increases rapidly with the increase of the oil film thickness. The experimental results show that the algorithm can effectively evaluate the thickness of spill film in the range of 200~1400μm on the sea surface, and the relative error of the oil film fluorescence signal can be used to evaluate the applicability of the algorithm.
		2020 Vol. 41 (11): 1327-1331 [Abstract] ( 275 ) HTML (1 KB) PDF (1066 KB) ( 400 )

	1332	Design and Implementation of High Precision Air Refractive Index Measurement System
		MIN Shuai-bo,YAN Li-ping,CUI Jian-jun,WANG Dong,SHU Hong-lin,CHEN Kai
		DOI: 10.3969/j.issn.1000-1158.2020.11.04
		Aiming at commercial air refractive index measuring device is affected by the acquisition performance of sensor and the accuracy of calculation formula, and its actual measurement accuracy is low. Based on portable multi-environmental parameter acquisition device, a set of air refractive index measurement system is designed to collect the information of temperature, humidity and atmospheric pressure in the environment. Error analysis of three indirect refractive index measurement formulas is carried out, and performance comparison with commercial environmental compensator is made. The experimental results show that under the experimental conditions of pressure 100.17~100.21kPa, temperature 21.1~21.9℃ and humidity 45.9~58.0% RH, the measurement error of the system is 2.69×10^-7 lower than that of the commercial environmental compensator.
		2020 Vol. 41 (11): 1332-1338 [Abstract] ( 341 ) HTML (1 KB) PDF (1473 KB) ( 934 )

	1339	Calibration and Traceability Method for Human Cornea Parameters
		ZHANG Ji-yan,LIU Wen-li,GAO Ming-liang,DING Xiang,SUN Jie
		DOI: 10.3969/j.issn.1000-1158.2020.11.05
		Corneal curvature radius, corneal refractive power and astigmatic axis are key parameters for evaluation of human corneal topography. In order to accurately measure and trace the human cornea parameters, based on the principle of human corneal reflection imaging, a series of standards for human corneal parameters were developed for the first time in the form of spherical and toroidal surface design. For curvature radius the measurement range is (5.5～10.0) mm and uncertainty is 0.002mm (k=2). While for axis the measurement range is (0°~180°) and uncertainty is 1° (k=2). Moreover, national standard for ophthalmometers has been established and traceability system for corneal parameters has been formed. Experimental results showed that the measurement standard and traceability system can meet the requirements of calibration and traceability of human corneal parameter instrument, and guarantee the accuracy of corneal parameter measurement.
		2020 Vol. 41 (11): 1339-1343 [Abstract] ( 305 ) HTML (1 KB) PDF (532 KB) ( 378 )

	1344	An Object Detection Method Based on Deep LearningUsing Feature Map Weighted Fusion
		ZHANG Shi-hui,WANG Hong-lei,CHEN Yu-xiang,LIU Xin-huan,
		DOI: 10.3969/j.issn.1000-1158.2020.11.06
		In order to improve the accuracy of object detection, a method based on deep learning using feature map weighted fusion is proposed. Firstly, the idea fusing the sampled shallow feature maps and the deepest feature map in the convolutional neural network is proposed. Secondly, the corresponding feature map weighted fusion scheme is developed according to the idea of feature map weighted fusion and the specific structure of convolutional neural network, and a new feature map is obtained from the scheme. Thirdly, an improved RPN network is proposed, and the new feature map is input into the improved RPN network to obtain the region proposals. Finally, the new feature map and the region proposals are input subsequent network layers to realize object detection. The experimental results show that the proposed method achieves higher object detection precision and better object detection effect.
		2020 Vol. 41 (11): 1344-1351 [Abstract] ( 312 ) HTML (1 KB) PDF (1728 KB) ( 303 )

	1352	Influence of Platinum Dislocation Characteristics on the Stability of Standard Platinum Resistance Thermometer
		GAO Kai,JIANG Qing,SUN Jian-ping,LI Xu,YE Meng,ZENG Jia-xu,GAO Zhi-han
		DOI: 10.3969/j.issn.1000-1158.2020.11.07
		Dislocation within platinum wire is one of the important factors affecting the stability of standard platinum resistance thermometers (SPRTs). From the microscopic point of view, the effect of annealing time on the dislocation density of platinum wire was studied by X-ray diffraction (XRD) analysis method, and verified by the SPRT annealing experimental data. The results show that the average dislocation density of the new platinum wire (purity 99.999%) with a diameter of 0.07mm goes down exponentially with the annealing time. After 100h annealing, the dislocation density decreases from 1012cm^-2 to 1011cm^-2, and then its dislocation density remains basically stable after 300h. The resistance of the new SPRTs have a significant decrease at the water triple point through previous 300h annealing, and the difference between before and after 300h annealing is less than 3mK and tends to be stable. The SPRTs annealing experiments and dislocation test results get good agreement at the heat treatment time. The research results provide technical support for the improvement of the standard platinum resistance thermometer manufacturing process and the revision of the metrological verification regulations.
		2020 Vol. 41 (11): 1352-1357 [Abstract] ( 243 ) HTML (1 KB) PDF (1277 KB) ( 299 )

	1358	Research on State Monitoring Method of Water Flow Standard Facility Based on Singular Value Decomposition
		SHI Hui-chao,KANG Xi-rui,MENG Tao
		DOI: 10.3969/j.issn.1000-1158.2020.11.08
		A signal separation method of flowmeter based on singular value decomposition is proposed to separate the flow signal, flow fluctuation signal and noise, and accurately obtain the flow fluctuation signals with different frequency and the relative amplitude of flow fluctuation in the pipeline of the flow facility, so as to realize the condition monitoring. The simulation results show that the flow fluctuation signals with different frequencies are separated accurately, and the maximum amplitude error is only 0.0681m³/h even when the noise variance is 1. Finally, the flow fluctuation signals with relative amplitude of 0.73% and 0.25% are separated by experiment, whose frequency are consistent with the frequency of flow fluctuation caused by pump instability and valve swing. Simulation and experiment results verify the feasibility of the proposed method.
		2020 Vol. 41 (11): 1358-1363 [Abstract] ( 313 ) HTML (1 KB) PDF (1778 KB) ( 657 )

	1364	Study on the Stack Cross Section Area Calibration Facility and Its Uncertainty Evaluation
		YANG Yang,ZHANG Liang,ZHANG Hong-jun,WANG Chi,KONG Hai-yan,ZHU Ze-jun
		DOI: 10.3969/j.issn.1000-1158.2020.11.09
		In order to ensure the accuracy of stack flowrate measurement based on velocity area method,it is necessary to accurately measure the stack cross section area.A stack cross section area calibration facility is developed,which can accurately measure the internal geometry of stack,and then calculat cross section area.At the same time,the cross section area fitting characteristics of random sampling method and least square method are discussed.After comparison and optimization,the maximum error of the average value of the fitted model is 0.02%,and the facility repeatability is 0.013%.Meanwhile the measurement uncertainty of the facility is evaluated,and the relative expended uncertainty is 0.17%(k=2).
		2020 Vol. 41 (11): 1364-1369 [Abstract] ( 225 ) HTML (1 KB) PDF (1385 KB) ( 294 )

	1370	All-Digital Drive Technology in Coriolis Mass Flowmeter
		XU Hao-ran,XU Ke-jun,LIU Wen,ZHANG Lun,YUE Jing,HUANG Ya,LIU Chen-ciXU Hao-ran¹,XU Ke-jun^1,2,LIU Wen¹,ZHANG Lun¹,YUE Jing¹,HUANG Ya¹,L
		DOI: 10.3969/j.issn.1000-1158.2020.11.10
		Aiming at the problem that the all-digital driving technology flow tube is difficult to start vibration, five kinds of starting methods such as analog to digital start-up, random wave start-up, sine wave start-up, sweep frequency square wave start-up, and positive-negative step alternate start-up are reviewed. Aiming at the problem that the amplitude, frequency and phase of driving signal are difficult to adjust, the solution is proposed. For the implementation platform of all-digital drive technology, two solutions are summarized: a single-core all-digital drive based on DSP and a dual-core all-digital drive based on DSP+FPGA. Among them, the single-core all-digital driving based on DSP has low cost and is easy to promote, and the dual-core all-digital driving based on DSP+FPGA has higher precision.
		2020 Vol. 41 (11): 1370-1379 [Abstract] ( 251 ) HTML (1 KB) PDF (536 KB) ( 446 )

	1380	Evaluation of Transfer Function of Resistance Strain Data Acquisition System
		LIANG Zhi-guo,SUN Hao-lin,YIN Xiao,WANG Ya-ting,WU Ya-hui
		DOI: 10.3969/j.issn.1000-1158.2020.11.11
		An identification method for the transfer function of the resistance strain data acquisition system is proposed. The detailed technical process is given, including the construction and assignment of the resistance strain step excitation source, the acquisition of the resistance strain step signal waveform, and the constant time delay of the strain amplifier. Measurement estimation, the measurement and the estimation of the constant time delay of the strain amplifier, the step response sequence of the resistance strain data acquisition system is obtained by equivalent sampling method, the timing sequence of the excitation sequence and the response sequence is unified and synthesized, and the transfer function of the resistance strain data acquisition system is performed by the least square method with a special whitening filter. The transfer function identification application in a set of experiments demonstrates the effectiveness and feasibility of the method described. The method can be used for the calibration of the dynamic characteristics of the resistance strain data acquisition system and its transfer function identification.
		2020 Vol. 41 (11): 1380-1385 [Abstract] ( 263 ) HTML (1 KB) PDF (1000 KB) ( 251 )

	1386	Research on Non-contact Speed Meter Comparison in China
		SUN Qiao,DU Lei,BAI Jie,CAO Jin,WANG Li-fang,SU Yang
		DOI: 10.3969/j.issn.1000-1158.2020.11.12
		The national comparison of non-contact speed meters was finished in 2018. The pilot lab was National Institute of Metrology, China. As the first comparison of fixed measurement spot type in on-site speed measuring metrology, 29 participating laboratories were involved, among which 27 were provincial level metrological institutes. All participating laboratories got satisfied results. The technical background and comparison program were introduced, the comparison method and uncertainty components were studied, the metrological particularities of speed measurement were proposed, and the comparison results were analyzed.
		2020 Vol. 41 (11): 1386-1390 [Abstract] ( 292 ) HTML (1 KB) PDF (313 KB) ( 239 )

	1391	Parameter Design and Characteristic Analysis of Torsional Vibration Damper for Main Drive System of Rolling Mill
		LIU Bin,WANG Ying-hui,JIANG Jia-lei,SHI Pei-ming
		DOI: 10.3969/j.issn.1000-1158.2020.11.13
		A torsional vibration damper control device is introduced for the torsional vibration phenomenon of the rolling mill main drive system under the sudden load of biting steel. Establishing torsional vibration suppression model of motor and torsional vibration damper. The characteristic parameters of the damper are designed. The inertia ratio, the tonal ratio and the damping ratio of the damper are obtained. Using the fixed point theory, the optimal tuning ratio and damping ratio are obtained. By comparing the time domain characteristic curves before and after adding the torsional vibration damper, it is concluded that the damper can reduce the vibration amplitude; By adjusting the inertia ratio, torsional stiffness and damping coefficient, the influence of different parameter changes on the amplitude-frequency characteristic curve of the rolling mill main drive system is obtained. Appropriate increase of inertia ratio μ can reduce the vibration amplitude, increasing the torsional stiffness Kd can reduce the unstable region of the system, increasing the damping coefficient Cd can effectively reduce the system torsional vibration amplitude. Therefore, selecting the appropriate parameter values can effectively improve the stability of the rolling mill system.
		2020 Vol. 41 (11): 1391-1397 [Abstract] ( 188 ) HTML (1 KB) PDF (779 KB) ( 310 )

	1398	Throughput Prediction of Port Based on Back Propagation Neural Network Optimized by Ant Colony Algorithm
		LI Chang-an,LU Xue-qin,WU Zhong-qiang,ZHANG Li-jie
		DOI: 10.3969/j.issn.1000-1158.2020.11.14
		Port cargo throughput is an important index of port production and operation scale, and it is the basis for port construction and development. In order to maximize the role of port, it is necessary to make a reasonable and effective forecast for port cargo throughput. Ant colony algorithm is used to optimize the initial weight and threshold of BP neural network, and the prediction model is established to predict the port cargo throughput. Ant colony algorithm has the characteristics of global search, distributed computation and strong robustness, which is beneficial to accelerate the convergence speed of BP neural network, avoids the problem of easy to fall into local extremum, and improves the modeling accuracy. The application in port throughput prediction shows that the average absolute percentage errors of BP neural network model optimized by ant colony algorithm, fuzzy neural network prediction model, RBF prediction model and BP prediction model are 2.826%, 3.734%, 4.990% and 6.566% respectively; meanwhile, the convergence speed of BP neural network model optimized by ant colony algorithm is the fastest.
		2020 Vol. 41 (11): 1398-1403 [Abstract] ( 278 ) HTML (1 KB) PDF (1036 KB) ( 309 )

	1404	Similar Frequency Signal Separation Based on VMD and Singular Value Decomposition
		XING Ting-ting,Guan Yang,LIU Zi-han,FAN Feng-jie,MENG Zong
		DOI: 10.3969/j.issn.1000-1158.2020.11.15
		Similar frequency signal separation is a difficult problem in fault diagnosis. As a new method of signal time frequency analysis, variational mode decomposition (VMD) has a higher resolution for signals with similar frequency. The number of decomposition levels, which can directly affect the decomposability, is first specified in VMD. Once over-decompose is likely to produce false frequency components, while under-decompose is easy to lose useful frequency components. Thus, a new method of similar frequency signal separation based on VMD and signal singular value decomposition is proposed. Firstly, appropriate decomposition levels is selected to over-decompose the signal, and then singular value decomposition is carried out on the components obtained by VMD, which can detect and eliminate false signal components, so as to separate similar frequency signal well. The effectiveness and feasibility of the proposed method are demonstrated by simulation signal and rolling bearing fault signal.
		2020 Vol. 41 (11): 1404-1409 [Abstract] ( 299 ) HTML (1 KB) PDF (2379 KB) ( 519 )

	1410	Triangular-wave Signal Driven Measuring Circuit in ECT
		MA Min,WU Ke,HU Ya-feng,CUI Zi-qiang,WANG Hua-xiang
		DOI: 10.3969/j.issn.1000-1158.2020.11.16
		Electrical capacitance tomography measuring circuit requires extremely high sensitivity and dynamic range. The use of triangular-wave signal as excitation signal was proposed to replace the sine-wave signal. Due to the differential characteristics of C/V converter circuit, its output became square wave signal when triangular-wave signal was applied to the measured capacitance. At the same time, the circuit showed good linearity in measuring small capacitance. Transient analysis showed that the settling time was reduced to 0.65μs. In addition, the capacitance acquisition rate could be greatly increased by the removal of phase sensitive detector. For a 12-electrode ECT system, the frame rate could reach up to 3124 frames/s. Experimental results showed that the peak peak value of the measurement sensitivity of the circuit is 0.8 V/pF, and the dynamic range is 69 dB.
		2020 Vol. 41 (11): 1410-1415 [Abstract] ( 281 ) HTML (1 KB) PDF (1159 KB) ( 346 )

	1416	Parameter Identification of Single-Phase Inverter Based on Improved Moth Flame Optimization
		WU Zhong-qiang,SHEN Dan-dan,SHANG Meng-yao,QI Song-qi
		DOI: 10.3969/j.issn.1000-1158.2020.11.17
		Based on the improved moth flame optimization algorithm, a parameter identification method of inverter circuit is proposed. Aiming at the shortcomings of the moth flame algorithm,at the early stage, the improved algorithm makes the moth move to the optimal position in a straight line and speeds up the convergence speed of the algorithm. At the later stage, the Levy flight is used to enhance the diversity of the population and improve the global search ability of the algorithm. The results of parameter identification show that the parameters identified by the improved algorithm are very close to the actual values, and the error is very small. The improved moth flame algorithm can effectively realize the accurate identification of inverter circuit parameters, and can be used in parameter fault diagnosis, operation status monitoring and predictive maintenance.
		2020 Vol. 41 (11): 1416-1424 [Abstract] ( 205 ) HTML (1 KB) PDF (1823 KB) ( 245 )

	1425	Evaluation of 60Co Nuclide Activity and Uncertainty by 4pβ(PC)-γ Coincidence Method
		TANG Hao,FAN Fu-you,LIANG Jun-cheng,ZHONG Ke,ZHU Bao-ji,YAO Shun-he,WANG Ren-bo
		DOI: 10.3969/j.issn.1000-1158.2020.11.18
		The 4Πβ(PC)-γ coincidence method is mainly used to achieve the absolute measurement of β-γ cascade decay radionuclide activity. This method generally measures the VYNS film source sample, This method is usually used to measure the VYNS film source sample, but its preparation process is complicated. This paper simplifies the source process. The source preparation process is optimized. The film source produced by the improved process is measured using a 4Πβ(PC)-γ digital coincidence system. The measurement results obtained by the efficiency extrapolation method show that the apparent efficiency of the new 60Co source reaches 93%, and the specific activity measurement results of the 10 sample sources are consistent within the range of 0.1%. By changing the resolution time, dead time and delay time on the digital compliance software, the influence of the parameter selection on the measurement results is studied, and the uncertainty of the 60Co nuclide activity measurement is evaluated.
		2020 Vol. 41 (11): 1425-1430 [Abstract] ( 300 ) HTML (1 KB) PDF (1043 KB) ( 225 )

	1431	Research on X-ray Attenuation Coefficient Measurement Method Based on Radiography
		YU Tuo-xia,XI Qing,YANG Dan
		DOI: 10.3969/j.issn.1000-1158.2020.11.19
		A method for calculating the attenuation coefficient of X-rays in matter by radiography was proposed. The attenuation coefficient of X-rays with different energies in matter was quickly obtained through simple experiments and calculation. The design experiment found out the relation curve between the blackness of the negative and the thickness of the workpiece, deduced the expression, and obtained the confidence interval of the expression. The X-ray attenuation coefficients of steel stepped test block at 140kV, 130kV and 120kV tube voltages were measured by radiographic method. The standard errors were less than 3%, which proved the reliability of the method. The X-ray radiography method is simple in calculation, convenient in operation and small in error. It is expected to be widely applied to the estimation of X-ray attenuation coefficient in materials.
		2020 Vol. 41 (11): 1431-1435 [Abstract] ( 284 ) HTML (1 KB) PDF (1147 KB) ( 503 )

	1436	Experimental Design Analysis of Developing Quantitative Nucleic Acid Reference Materials
		LI Da,WANG Jun,YANG Zhong,WANG Hui-ru
		DOI: 10.3969/j.issn.1000-1158.2020.11.20
		With the rapid development of molecular in-vitro diagnostics diagnostic (IVD) technology, the market demand for different types of traceable nucleic acid reference materials (RMs) is becoming more and more urgent. However, the diversifying demands for IVD products make it difficult to develop nucleic acid RMs. Fortunately, the physical-chemical characteristics of nucleic acids are similar, and there are many common points in the quantitating process. nucleic acids have many similar physical-chemical characteristics and have a lot in common in the quantitating process. Four ctritical factors were elaborated about quantitative experiments in developing process of nucleic acid RMs, which contain nucleic acid sampling volume, dilution, selection of certification method and data analysis. It can be concluded that the sampling volume, loading concentration and optimizing quantitative range of instruments are critical to establish the correct experiment system. Thus, the experimental error in the nucleic acid quantitating process can be reduced and the wrong results can be avoided.
		2020 Vol. 41 (11): 1436-1442 [Abstract] ( 285 ) HTML (1 KB) PDF (1392 KB) ( 322 )

	1443	Pressure Compensation Method on Aircraft Cabin Air Quality Detection
		HE Yong-bo,TIAN Ji-lei,HUANG Lü-lin,LI Ming-wei
		DOI: 10.3969/j.issn.1000-1158.2020.11.21
		The larger aircraft cabin air pressure range had great influence on the gas sensor, resulting in inaccurate air quality detect results, RBF neural network was proposed to compensate air pressure. Firstly, the experimental system was designed. Then positive and negative pressure experiments were carried out on four typical gas sensors for cabin air quality detection including HCHO, CO, CO2 and NO2. The test data were collected and the characteristic curves of each gas were drawn. Finally, a three-layer RBF neural network model with 12 pressure points and measured values as inputs and expected values as outputs was established, and the error correction compensation was made to the experimental data. The results showed that the RBF neural network compensation algorithm can reduce the maximum relative error of HCHO, CO, CO2 and NO2 gas sensors from 32.85%, 28.42%, 52.87%, 87.18% to 2.001%, 3.668%, 2.392%, 12.68% respectively, achieve a better compensation effect.
		2020 Vol. 41 (11): 1443-1448 [Abstract] ( 234 ) HTML (1 KB) PDF (1424 KB) ( 251 )

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