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2020 Vol. 41, No. 5 Published: 2020-05-28

	513	Antigen and Antibody Detection of SARS-CoV-2
		GAO Yuan,CHEN Chuan,WANG Jing
		DOI: 10.3969/j.issn.1000-1158.2020.05.01
		2019 novel coronavirus (SARS-CoV-2) invades the human body and causes an acute respiratory infectious disease, which was named as Corona Virus Disease (COVID-19). The global spread of SARS-Cov-2 poses a huge threat to global public health security. The detection of SARS-CoV-2 is particularly important for disease diagnosis. Immunoassay method has played a role in clinical diagnosis as an aid to virus nucleic acid detection. Immuno-diagnostic techniques include antibody and antigen detection, and determine whether the virus are carried by detecting the viruss own protein and antibody. Analysis was focused on the current immunoassay methods for SARS-CoV-2.
		2020 Vol. 41 (5): 513-517 [Abstract] ( 346 ) HTML (1 KB) PDF (464 KB) ( 1246 )

	518	Technology of Size Detection of Air Rivets Based on Machine Vision
		XING Xue-liang,GAN Wen-bo,JIANG Chao-gen
		DOI: 10.3969/j.issn.1000-1158.2020.05.02
		The size error of air rivets can increase the possibility of aviation accidents. To enhancing the precision and intelligence of size detection for air rivets, a kind of method based on machine vision was used. The size error of air rivets can be eliminated by the automatic identification and detection of rivets depending on the edge detection algorithm. Based on the production standards of air rivets, the requirements of various dimensional parameters and the processes of the events were obtained. Using OpenCV as the development platform, the image segmentation was finished by the threshold segmentation algorithm and watershed algorithm. Meanwhile, the image processing was completed by smoothing, morphology and contour extraction algorithm. The test results showed that the accurateness of the size results with the actual value was more than 90% under the accuracy of ±0.005mm.
		2020 Vol. 41 (5): 518-523 [Abstract] ( 402 ) HTML (1 KB) PDF (1350 KB) ( 1438 )

	524	Study on Approaching Characteristics between the Tip and the Surface of Atomic Force Microscope Based on Tuning Fork Probe
		SHI Hui,GAO Si-tian,HUANG Lu,SHEN Xiao-yan
		DOI: 10.3969/j.issn.1000-1158.2020.05.03
		In the study of atomic force microscopy, the micro-force detection in the approaching process between the tip and the sample is the basis for accurate measurement of the sample morphology. A dynamic equation was established based on the characteristics of tuning fork probe and Simulink software was used to simulate the amplitude response. Experimental device of approaching curve and program of controlling displacement system and acquiring data from lock-in amplifier were designed independently. In the AM mode, the curves under different excitation voltages were obtained. Under the excitation of 25, 50, 75 and 100mV, the working distance of the probe is 4.12,5.1,5.95,7.6nm respectively, and the forms are in conformity with the simulation.
		2020 Vol. 41 (5): 524-528 [Abstract] ( 316 ) HTML (1 KB) PDF (728 KB) ( 406 )

	529	Accurate Measurement of Nanoparticles By Using Multi-angle Dynamic Light Scattering

		DOI: 10.3969/j.issn.1000-1158.2020.05.04
		Based on the principle of dynamic light scattering, an independent multi-angle dynamic light scattering device was used to investigate the accurate measurement methods of nano and submicron particle size. The precision incident light path design with diaphragm group, matching liquid pool and beam-stop design were adopted in the self-developed device, which greatly improved the signal-to-noise ratio. At the same time, the interference of the reflected light signal caused by the different refractive index between the sample cell and the air interface in the complementary direction of the measurement angle was avoided. On this basis, the polystyrene (PS) particle solution with different concentration and particle size was determined and its uncertainty was analyzed. The results showed that for PS particles with the same particle size, multiple scattering first occurs at large and small measurement angles when the particle concentration is increased. The closer to 90°, the higher the multiple scattering concentration is. With the increase of particle size, the particle size measurement results showed a strong angular dependence and even volatility due to the non-negligible interaction between particles.
		2020 Vol. 41 (5): 529-537 [Abstract] ( 344 ) HTML (1 KB) PDF (3334 KB) ( 937 )

	538	Smoking Detection Algorithm Based on Multitask Classification
		CHENG Shu-hong,MA Xiao-fei,ZHANG Shi-jun,ZHANG Li
		DOI: 10.3969/j.issn.1000-1158.2020.05.05
		In order to detect the smoking behavior in time and accurately judge the state. A smoking behavior detection algorithm based multi-task classification was proposed. The algorithm integrates multi-task convolution neural network, ensemble of regression trees cascade regression and depth residual network, quickly and accurately locates the region of interest through multi-task convolutional neural network algorithm and ERT cascade regression. Based on this, detect targets in the region of interest and identify status using deep residual network. The experimental results showed that the algorithm can accurately detect the occurrence of smoking behavior and make state judgments, the accuracy rate can reach 87.5%.
		2020 Vol. 41 (5): 538-543 [Abstract] ( 337 ) HTML (1 KB) PDF (1757 KB) ( 866 )

	544	Method for Detecting Internal Defects of Metal Lattice Structure Based on CT Images
		ZHANG Yu-yan,LI Yong-bao,WEN Yin-tang,ZHANG Zhi-wei
		DOI: 10.3969/j.issn.1000-1158.2020.05.06
		Based on the gray value distribution characteristics of computed tomography (CT)scanning images, a method for detecting the internal defects of metal three-dimensional multi-layer lattice structures was proposed. The defects was detected by the distribution of the difference between the gray values of the three horizontally adjacent fixed-size pixel points, and the corresponding criteria and basis were given by theoretical analysis. The experiment results showed that, compared with the method by artificial markers, the proposed algorithm can accurately identify the typical chasm defects inside the metal three-dimensional multi-layer lattice structure, and the recognition rate reaches 98.5%.
		2020 Vol. 41 (5): 544-550 [Abstract] ( 321 ) HTML (1 KB) PDF (1609 KB) ( 368 )

	551	Camera Pose Estimation Based on Quaternion from Least Feature Points
		HOU Pei-guo,ZHAO Zi-jian,SONG Tao
		DOI: 10.3969/j.issn.1000-1158.2020.05.07
		In order to solve the problem of camera pose estimation, a algorithm based on quaternion from least feature points was proposed. A polynomial system, established by constraints and feature points which were detected and matched in the two-dimensional image, was solved by corresponding matrix equation. Using quaternion to represent the rotation of the camera, which avoided the entanglement between rotation and translation in the process of solving. When the translation between two views is equal to zero, the problem can be solved well. The algorithm was deduced in detail by combining five-point algorithm and the anti-noise test was carried out. In the test, as the number of matched feature points increases, the average estimated error range of the algorithm does not exceed 2%. The KITTI dataset was used to test the usefulness of the algorithm and compare the results with several other methods. The results showed that under the same conditions, the algorithm improves the estimation accuracy by more than 24.5%, which shows a good estimation accuracy.
		2020 Vol. 41 (5): 551-557 [Abstract] ( 267 ) HTML (1 KB) PDF (951 KB) ( 481 )

	558	Error Analysis of CCD-Based Thermoreflectance Microscopy
		LIU Yan,ZHAI Yu-wei,LI Hao,HAN Wei,JING Xiao-dong,LIANG Fa-guo
		DOI: 10.3969/j.issn.1000-1158.2020.05.08
		Thermoreflectance includes two major procedures, namingly CTR calibration and temperature measurement. Several measured quantities and influencing factors are involved in each procedure. Error analysis on measured quantities involved with CTR calibration and temperature measurement procedure were present. Moreover, fixed bias on CCD count and drift of light source and camera responsiveness were included in the analysis as well. Approximate calculation with typical parameters were carried on according to the result of the analysis, and the discussion were made can provide some reference for the design, construction and application of the CCD-based thermoreflectance systems.
		2020 Vol. 41 (5): 558-562 [Abstract] ( 253 ) HTML (1 KB) PDF (399 KB) ( 231 )

	563	Study on Dynamic Characteristics of Temperature Sensors under Different Heat Transfer Modes
		JIA Chao,CAI Jie,XIONG Zhao-hui
		DOI: 10.3969/j.issn.1000-1158.2020.05.09
		In order to study the influences of the heat transfer modes on the dynamic characteristics of temperature sensors, the relationship between the heat transfer mode and the dynamic characteristics of temperature sensors was derived by the theory of time constant, and the dynamic characteristics of temperature sensors were analyzed under different heat transfer modes. The heat transfer models of the temperature sensors were established with the modes of convection heat transfer and radiation heat transfer, and the thermocouple time constant were tested via the oil bath method and the pulsed laser method. The test results showed that the time constant test values of the thermocouple in convection heat transfer and radiation heat transfer mode are 1.2s and 6.2s respectively. It can be seen that the heat transfer mode directly affects the dynamic characteristics of the temperature sensor, and finally the rationality of the heat transfer model can be verified by comparing the test values and the theoretical calculations values.
		2020 Vol. 41 (5): 563-566 [Abstract] ( 411 ) HTML (1 KB) PDF (698 KB) ( 759 )

	567	Stack Flowrate Standard Facility
		DENG Qian-feng,ZHANG Liang,FANG Li-de,WANG Chi,LIU Yang
		DOI: 10.3969/j.issn.1000-1158.2020.05.10
		In order to solve the problem of traceability of stack flowmeter, a stack flowrate standard facility was developed in National Insititute of Metrology. The facility uses a laser Doppler velocimeter which is calibrated by a spinning disk to traceable to SI unit as primary standard meter. The laser Doppler velocimeter was used to scan the flow profile and an ultrasonic flowmeter was used to correct the flow fluctuation. After calibrated by the laser Doppler velocimeter, the 8-path ultrasonic flowmeter is used as the working standard, the flow range is 908~104840m3/h, the expanded uncertainty of the facility is 0.62% (k=2), it can calibrate the flowmeter with a largest diameter of 1 meter. The test section of the facility includes circular pipelines and a rectangular pipeline, which can study the measurement performance of stack flowmeters.
		2020 Vol. 41 (5): 567-572 [Abstract] ( 301 ) HTML (1 KB) PDF (1087 KB) ( 515 )

	573	Design of Neural Network Algorithm for Dynamic Weighing of Belt Weigher
		DONG Xiang-chen,LI Bing-ying,LI Yong-xin,WANG Hai-tao
		DOI: 10.3969/j.issn.1000-1158.2020.05.11
		To improve the weighing precision of the belt weigher, it was proposed to introduce process neural network (PNN) to compensate the dynamic weighing error of belt weigher. The weight per unit length of the belt weigher, speed of belt, and variation in belt sag in dynamic weighing process were used as model input. The single hidden layer PNN error back propagation learning algorithm was designed to apply to the study of the dynamic weighing error of the belt weigher. The algorithm model was trained and tested by MATLAB software and the model achieved network accuracy requirements after 149 learning optimizations. The test group error reaches 1%, which is significantly lower than the original error before using the network, and verifies the feasibility and effectiveness of the algorithm.
		2020 Vol. 41 (5): 573-577 [Abstract] ( 349 ) HTML (1 KB) PDF (516 KB) ( 700 )

	578	Research on the Characteristic Tuning System of the New Rotating Angular Acceleration Sensor
		LU Sheng-kang,FENG Hao,ZHAO Hao
		DOI: 10.3969/j.issn.1000-1158.2020.05.12
		A set of characteristic calibration system was constructed for the calibration problem of rotating angular acceleration sensor. Firstly, the working principle of permanent magnet rotating angular acceleration sensor was analyzed. A pure angular single-phase, adjustable frequency amplitude modulated angular acceleration pulse source system based on frequency-modulated voltage-regulated power supply was proposed. Then the traditional incremental type was adopted, a rotating angular acceleration measurement system was constructed by the grating encoder and FPGA. Finally, the output characteristics of the sensor were calibrated by comparing the peak value of the output voltage of the rotating angular acceleration sensor with the peak value of the actual angular acceleration of the measurement system. The relation curve between the output voltage and the angular acceleration was obtained, the linear error of which is 1.81%.
		2020 Vol. 41 (5): 578-584 [Abstract] ( 276 ) HTML (1 KB) PDF (1240 KB) ( 446 )

	585	Fault Diagnosis of Submersible Pumps Based on Local Mean Decomposition and Fast Independent Component Analysis
		TIAN Li-yong,ZHANG Yi-zhe
		DOI: 10.3969/j.issn.1000-1158.2020.05.13
		Aiming at the signal interference problem in fault diagnosis and analysis of submersible pumps, a method of combining local mean decomposition with independent component analysis was proposed. A series of product function components were obtained by decomposing the local mean value of the collected vibration signal, and the cross-correlation coefficient between each component and the vibration signal was calculated. The components with large cross-correlation number were selected to reconstruct and a matrix with the vibration signal was formed. The matrix was processed by fast independent component analysis, and the processed effective data was analyzed by spectrum analysis to get the final spectrum. Through specific experiments, the spectrum diagram of normal operation and fault operation after local mean decomposition and independent component analysis were compared, and the fault analysis and diagnosis were realized. Experimental results showed that the spectrum diagram processed by local mean decomposition and independent component analysis can clearly distinguish the fault characteristic frequency and improve the accuracy of fault diagnosis.
		2020 Vol. 41 (5): 585-591 [Abstract] ( 275 ) HTML (1 KB) PDF (771 KB) ( 204 )

	592	Calibration Method for Resistance Parameters of Battery Internal Resistance Testers Based on AC Injection Method
		FENG Jian,HU Jun-jie,HU Bin
		DOI: 10.3969/j.issn.1000-1158.2020.05.14
		The principle of AC internal resistance measurement function of battery testers was analyzed. The calibration method based on AC standard resistor and inductive voltage divider was researched. A multi-decades two-stage inductive voltage divider was used to change the voltage of AC standard resistor in proportion. As a result, a high accuracy AC resistance box with multi-decades was simulated, which solved the problem of lack of standard for the calibration of battery internal resistance testers. The influence of both the time constant of AC resistor and phase error of inductive voltage divider was analyzed. The calibration results of the mentioned method and that used the physical resistors were compared. The difference was less than 0.02% over the full scale range, which proved the high accuracy of the above method.
		2020 Vol. 41 (5): 592-596 [Abstract] ( 276 ) HTML (1 KB) PDF (744 KB) ( 452 )

	597	The Influence of the Flat Electrode in the Calibration Device of Electrostatic Voltmeter on the Potential Distribution
		SHI Peng-fei,NI Da-zhi,WANG Xiao-wen,ZHAO Wei
		DOI: 10.3969/j.issn.1000-1158.2020.05.15
		The plate electrode is an important part of the calibration device of electrostatic voltmeter. Its geometric parameter affects the potential distribution around it. Through theoretical analysis and simulation, the influence of the diameter, shape, thickness, edge smoothness and height of the plate electrode on the electric potential distribution is analyzed and calculated. The circular plate electrode with a distance of 100mm、a diameter of 600mm and a thickness of 1mm is a reference, the calculation results show that the potential distribution on the axis increases by only 1.3% when the diameter increases to 1000mm, the potential distribution increases by more than 5.4% when the thickness of the flat electrode increases by 100mm, which is closer to the potential distribution generated by the infinite plate electrode. When the size is equal, the influence of shape on the distribution of electric potential can be neglected; the influence of edge smoothness on the distribution of electric potential can be neglected; 0.5 meters from the ground will form a distinct distortion potential distribution. The numerical calculation results can be used as a reference for the design of plate electrodes in the calibration device.
		2020 Vol. 41 (5): 597-601 [Abstract] ( 317 ) HTML (1 KB) PDF (1288 KB) ( 297 )

	602	A New Type of AC Impedance Measurement Standard Device
		YAN Xiao-jun,HU Bei-bei,LI Ya-lu,WU Kang,YOU Li
		DOI: 10.3969/j.issn.1000-1158.2020.05.16
		A new type of AC impedance measurement standard is developed, which can resolve the traceability problem of AC impedance by producing any amplitude and angle. Between 100Hz to 1MHz, 0.1Ω to 10kΩ, the new type of AC impedance measurement standard, which is composed of AC impedance standard source and meter, can calibrate RLC digital meter, AC impedance and material impedance, and the best accuracy is 0.01%. By using direct measurement, substitution measurement and equipotential measurement, AC impedance measurement standard can be traced to material impedance standard, voltage ratio standard and phase standard. Thus a traceability chain of AC impedance is formed.
		2020 Vol. 41 (5): 602-607 [Abstract] ( 315 ) HTML (1 KB) PDF (495 KB) ( 287 )

	608	Research on Generation of Digital Modulation Signals with EVM Controllable
		YU Qing-hua,SHEN Xiao-qing,CONG Bo,WANG Tian-yun,QIU Bin,CHEN Si
		DOI: 10.3969/j.issn.1000-1158.2020.05.17
		To solve lacking of device which can cover the EVM range of digital signals in the intermediate checks of calibration equipment of digital signal generator and signal analyzer, an analytical relation between SNR and EVM was derived. A system based on noise generator and digital signal generator was proposed which can generate digtal modulation signals with any EVM value. To verify the repeatability and stability of the output of the system, experiments were performed, BPSK and 64QAM signals were tested, and results showed that even though the values between the theory and the measured were not the same, the output of the sytem was very stable, the repeatability and stability of the output qualified with needs of the intermediate checks of calibration equipment of digital signal generator and signal analyzer.
		2020 Vol. 41 (5): 608-613 [Abstract] ( 264 ) HTML (1 KB) PDF (471 KB) ( 274 )

	614	Research on Network Online Testing Technology for Main Station of Power Distribution Automation System
		XI Yu,CHEN Bo,YUAN Zhi-yong,CHEN Hao-min,JIANG Yu-yong,YANG Zhan-jie,WANG Jian-bang
		DOI: 10.3969/j.issn.1000-1158.2020.05.18
		Aiming at the difficulty of testing and verifying the function and performance of the main station of distribution automation system effectively and quickly, a networked online test system for the main station of the distribution automation system was designed. The overall architecture of the networked online simulation test platform was described, and its basic functional modules and software implementations were described in detail. The networked test environment and method of distribution automation master station system were analyzed in detail, and the performance index test, avalanche test, stability test, reliability test, safety test and maintainability test of the main station were elaborated. The test system can meet the standards and requirements of the distribution automation system on-line detection, and provids an important guidance for the operation and maintenance of the main station system.
		2020 Vol. 41 (5): 614-619 [Abstract] ( 241 ) HTML (1 KB) PDF (1255 KB) ( 312 )

	620	Research on Intelligent Diagnosis of Atrial Fibrillation Based on One-dimensional Convolution Neural Network
		XIE Sheng-long,ZHANG Wei-min,LU Yu-jun,ZHANG Wen-xin,ZHU Jun-jiang,REN Guo-ying
		DOI: 10.3969/j.issn.1000-1158.2020.05.19
		Aiming at the problem of how to use data to diagnose atrial fibrillation intelligently and efficiently in the era of “big data”, an intelligent fault diagnosis method based on one-dimensional LeNet-5 convolution neural network(CNN) is proposed to avoid the problem that traditional algorithms rely on artificial feature extraction and prior knowledge. Firstly, one-dimensional LeNet-5 and AlexNet neural network models are constructed, and network structure parameters are set reasonably. Then, a series of data processing is carried out according to the characteristics of ECG signals based on the collected experimental data, and training samples and test samples are constructed randomly. Finally, the training samples are input into the above two convolution neural network models for training and learning, and the trained model is applied to the diagnosis of atrial fibrillation. The experimental results show that the one-dimensional LeNet-5 network model has the phenomenon of “over-fitting”, while the one-dimensional AlexNet network model avoids the above phenomena and achieves a diagnostic accuracy of 95.34%. Compared with the traditional methods, the intelligent diagnosis method has been improved accuracy greatly, and it provides effective means for the identification of atrial fibrillation.
		2020 Vol. 41 (5): 620-626 [Abstract] ( 256 ) HTML (1 KB) PDF (1642 KB) ( 875 )

	627	Estimation of the Minimum Detectable Activity of a Plastic Scintillator-type Car-borne Radioactive Detection System
		LU Xiao-jun,XIN Zhi-wei,HE Lin-feng
		DOI: 10.3969/j.issn.1000-1158.2020.05.20
		The main features of the plastic scintillator-type car-borne radioactive detection system was introduced. Through the combination of theoretical model and experiment, the measurement feasibility and estimation measurement method of the minimum detectable activity (MDA) were studied. The results showed that: (1) when estimating the MDA of the plastic scintillator-type car-borne radioactive detection system, the activity response should be measured within 20m from the car body; (2) The relationship between the reference activity response and the distance x is a two-element addition model, from which the minimum detectable activity at a specific location can be estimated or minimum detectable distance of the Car-borne radioactivity detection system can be estimated if the reference source activity is known. The MDA estimation method established by the research can provide reference for the technical performance evaluation and application of the plastic scintillator-type car-borne radioactive detection system.
		2020 Vol. 41 (5): 627-632 [Abstract] ( 286 ) HTML (1 KB) PDF (1151 KB) ( 224 )

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