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2024 Vol. 45, No. 1
Published: 2024-01-28
 
1 Test Method of In-plane Thermal Conductivity of Thin Films Based on Laser Thermal Imaging
CHEN Mingxin,HOU Dexin,YE Shuliang
DOI: 10.3969/j.issn.1000-1158.2024.01.01
A laser-based heat flow loop integration test method is proposed to simulate and demonstrate the difference in heat loss between laser heating and conventional electrical heating solutions; the calibration of key parameters such as laser heating power, surface heat transfer coefficient and temperature measurement model gain coefficient are analysed and the corresponding methods are designed. The experiments are based on 15 thin films and sheets of different materials or thicknesses, and the relative deviations between the test results and the reference values are less than 6%. The test errors of samples with thermal conductivity less than 3W/(m·K)are significantly better than those of the conventional method, indicating that the method can effectively improve the test accuracy of the heat flow loop integration method for low thermal conductivity films.
2024 Vol. 45 (1): 1-8 [Abstract] ( 118 ) HTML (1 KB)  PDF (590 KB)  ( 96 )
9 Global Thermal Network Model for Oil-immersed Transformers
LU Fei,SU Xiang,LI Hua,LIN Fuchang,LU Yangze
DOI: 10.3969/j.issn.1000-1158.2024.01.02
The hot spot temperature is an important index to measure the insulation performance and safety margin of the transformer. It is of great significance to calculate it quickly and accurately. We analyzes the heat generation and heat transfer mechanism inside the oil-immersed transformer, the relationship between the velocity and temperature distribution and the fluid Prandt number Pr in the natural convection boundary layer are obtained. Considering the axial variation of local natural convection heat transfer coefficient and the difference of heat transfer characteristics in different regions, the oil-immersed transformer is divided and layered. Based on the thermoelectric analogy method, multiple types of thermal resistances are defined, and the global thermal network model of the oil-immersed transformer is constructed. The calculation results of the thermal network model are compared by finite element simulation. The temperature change trend of the windings obtained by the two is the same. The difference of the hot spot temperature is about 1.9%, and the difference of the hot spot position is about 7.7%. Compared with finite element simulation, the thermal network model has more advantages in solving time and efficiency. It can realize online monitoring, real-time analysis and dynamic evaluation of the operating status of oil-immersed transformers.
2024 Vol. 45 (1): 9-17 [Abstract] ( 76 ) HTML (1 KB)  PDF (717 KB)  ( 81 )
18 Position and Attitude Measurement Method of Track Inspection Vehicle Bogie Based on Multi-Sensors
ZHANG Xin,HAN Zhi,CHEN Chunlei,LUO Zai,JIANG Wensong
DOI: 10.3969/j.issn.1000-1158.2024.01.03
Aiming at the problem that the frame motion of the track inspection vehicle affects the measurement accuracy of the track geometry detection system, a method of frame pose measurement based on multi-sensor fusion is proposed. In this method, acceleration sensor and biaxial inclination sensor are used to collect the original signal of the frame pose. Then, the original signals collected by multiple sensors are fused and solved by the method of solving the pose of the center of the frame. Finally, the geometric center pose of the frame is obtained. Under the circumstance, verification and adaptability experiments separately based on laboratory and national railway track test center calibration line are conducted.The results shows, the 95th percentile errors of measured lateral distance、 vertical distance、 roll angel and yaw angle are less than 0.88 mm、0.44 mm、0.07°、0.04°, respectively, in comparison with standard values, while the corresponding 95th percentile differences of measured position and attitude data and track inspection data are no more than 0.99 mm、0.73 mm、0.08°, which turns out the method is available to measure track geometry train bogies position and attitude accurately, so as to tell track disease and improve the efficiency of track inspection subsidiarily by applying to commercial vehicles.
2024 Vol. 45 (1): 18-23 [Abstract] ( 131 ) HTML (1 KB)  PDF (615 KB)  ( 110 )
24 Precise Measurement of Terahertz Divergence Angle for Conical Surface Fitting
LI Yatian,FANG Bo,WU Jialu,FANG Can,CAI Jinhui
DOI: 10.3969/j.issn.1000-1158.2024.01.04
Aiming at the precise measurement of terahertz(THz) beam divergence angle, a terahertz divergence angle measuring facility based on conical surface fitting was constructed based on single-frequency continuous wave terahertz source. By investigating the propagation mode of terahertz beam and analyzing its spatial characteristics of intensity distribution, the terahertz output beam is regarded as the conic surface in the far field range, and the spot image is collected by a terahertz detector, and the conic surface is constructed according to the coordinates of the edge points of the image. By means of indirect adjustment, the data of edge points are preprocessed and parameter iteration and conical surface fitting are used to calculate the divergence angle. The results show that the terahertz source divergence angle of 100GHz is 2.73°, and the relative expanded uncertainty is 3.8% (k=2).
2024 Vol. 45 (1): 24-29 [Abstract] ( 75 ) HTML (1 KB)  PDF (507 KB)  ( 61 )
30 Application of Improved YOLOX in Inshore Ship Inspection
ZHANG Liguo,ZHAO Jiashi,JIN Mei,ZENG Xin,SHEN Minghao
DOI: 10.3969/j.issn.1000-1158.2024.01.05
To solve the problems of large changes in target scale and serious environmental interference during nearshore ship detection, an improved anchorless frame detection algorithm of YOLOX is proposed. Firstly, the contextual transformer (CoT) module is introduced in the backbone network to enhance the expression capability and improve the problem of severe environmental interference by dynamically using contextual information. Secondly, SimAM attention is embedded between the feature pyramid and detection head to enrich semantic information and improve small target detection accuracy. Furtherly, CIOU is used to replace the original loss function to improve the convergence speed. Finally, the depth-separable convolution is used to replace the ordinary convolution in the feature pyramid to reduce the number of parameters and improve the detection speed. The experimental results show that on the SeaShips dataset, the improved model improves the accuracy by 6.73%, mAP reaches 96.63%, and detection speed reaches 48.6 frames per second while reducing the number of parameters, which can detect near-shore ships in real time and with high accuracy.
2024 Vol. 45 (1): 30-37 [Abstract] ( 108 ) HTML (1 KB)  PDF (878 KB)  ( 177 )
38 An Image Fusion Method of Reconstructed Images for Combined-electrode Electrical Capacitance Tomography
ZHANG Lifeng,ZHAO Jianhai,HUA Huichun
DOI: 10.3969/j.issn.1000-1158.2024.11.06
One kind of image fusion method of electrical capacitance tomography (ECT) based on the reconstructed images of combined-electrode ECT and hierarchical clustering is proposed. Firstly, the combined 8-electrode and 12-electrode array sensors of ECT are constructed, and the excitation measurement schemes of the two combined sensors are studied; Secondly, the hierarchical clustering method is used to cluster the reconstructed images of the two combined electrodes, so as to eliminate the artifacts in the reconstruction process; Finally, the wavelet fusion is carried out using the two clustered images. Experimental results show that compared with the initial reconstructed images, the average relative error is the smallest with the maximum decrease being 23.4%, while the average correlation coefficient is the largest with the maximum increase being 10.56%
2024 Vol. 45 (1): 38-43 [Abstract] ( 75 ) HTML (1 KB)  PDF (550 KB)  ( 68 )
44 A Dynamic Measurement Method of Gravity Gradient Based on Torsion Balance
YE Ziwei,WANG Fei,BAO Fu,HUANG Anyi,YU Ye,HU Hongbo,WANG Ruolin
DOI: 10.3969/j.issn.1000-1158.2024.01.07
To study the problem that the traditional torsion balance gravity gradiometer has high accuracy but poor stability and low measurement efficiency,introducing the dynamic modulation method and applying the Z-type torsion balance structure to the dynamic measurement mode to realize the simultaneous measurement of gravity horizontal gradient and gravity curvature. Using rotating filter and genetic algorithm in the process of signal processing can effectively eliminate the influence of free oscillation of torsion pendulum on target peak value and extract the amplitude and phase of target frequency. The simulation results show that the uncertainty component introduced by the genetic algorithm to extract the target gravity gradient value from the dynamic measurement mode signal does not exceed 0.0077E(1E=10-9/s2). When genetic algorithm is used for data post-processing,the measurement uncertainty of the system is evaluated as 0.0582E.
2024 Vol. 45 (1): 44-51 [Abstract] ( 91 ) HTML (1 KB)  PDF (528 KB)  ( 80 )
52 Study on Electrostatic Self-Calibration Method of Piezoelectric Accelerometer
CHEN Le
DOI: 10.3969/j.issn.1000-1158.2024.01.08
In order to solve the problems of accelerometer difficulty in achieving regular calibration, high calibration cost,and difficulty in meeting long-term work needs, the self-calibration method of piezoelectric accelerometer with drive port is studied. The principle of self-calibration method simulating external vibration excitation and the conversion sensitivity laboratory measurement method of the internal drive piezoelectric element of the sensor are explained, and based on the inverse piezoelectric effect of the driving piezoelectric element, the on-site in-situ calibration of the accelerometer can be realized by the electrical excitation of the sensor drive port,and the calibration results of the shaker calibration method are compared. The experimental results show that in the frequency range 5~10000Hz, the self-calibration sensitivity results are consistent with the vibration table sensitivity calibration results,and the error is within±2%,which verifies the effectiveness of the method.
2024 Vol. 45 (1): 52-56 [Abstract] ( 79 ) HTML (1 KB)  PDF (380 KB)  ( 213 )
57 International Key Comparison of Shock Acceleration and Determination of the Reference Value
HU Hongbo,BAI Jie,SUN Qiao
DOI: 10.3969/j.issn.1000-1158.2024.01.09
The National Institute of Metrology, as pilot laboratory for the first international key comparison for shock acceleration(CCAUV.V-K4) is proposed. Technical protocol is illustrated by combination of dynamic characteristics of shock acceleration measuring chain and spectral contents of shock excitation. Three different approaches are used to calculate the reference value of comparison, including recommended method by international comparison and two methods based on Bayesian inference. It is argued that Bayesian approach with different statistical model is compatible with the practice of metrology, with different prior distribution and MCMC method to obtain the posterior distribution. The equivalence and divergence of three methods are illustrated through comparison of results obtained.
2024 Vol. 45 (1): 57-63 [Abstract] ( 82 ) HTML (1 KB)  PDF (634 KB)  ( 35 )
64 Research on Mixed Overlapping Group Sparse for Multi-source Acoustic Emission Signal
DENG Tao,LIU Zhechao, WANG Huazhang,HE Lei
DOI: 10.3969/j.issn.1000-1158.2024.01.10
Acoustic emission detection of high-speed train body cracks involving multiple sources, overlapping wave modes, and noise interference, a mixed overlapping group sparse (MOGS) classification method with intrinsic mode function (IMF) is proposed for the identification of acoustic emission sources. MOGS is a structured sparse model that involve inter-and intra-group sparsity while allowing feature overlap between classes. A new noise pre-decomposition matrix is designed to reduce the computational complexity of IMFs. The IMF that include eigenfrequencies was selected as the sample to improve the difference between classes. MOGS dictionary was trained by the K-SVD with hierarchical group sparse lasso penalty function, and a separable block coordinates with approximate smoothing process method was proposed to solve MOGS lasso penalty function. Experiments show that the classification accuracy of this method is higher than 80%, the identification rate and waveform reconstruction effect are better than other algorithms.
2024 Vol. 45 (1): 64-72 [Abstract] ( 70 ) HTML (1 KB)  PDF (804 KB)  ( 55 )
73 Real-time Energy Distribute Strategy of PHEV Hybrid Energy Storage System Based on Stacking Fusion Model
WU Zhongqiang,MA Boyan
DOI: 10.3969/j.issn.1000-1158.2024.01.11
In order to solve the problem of low specific power of the single-power battery that unable to respond to transient power demand in plug-in hybrid electric vehicle, a hybrid energy storage system with parallel connection between battery and supercapacitor was designed. To the problem of lack real time when using dynamic programming (DP) method to optimize load current distribution, a training set composed of DP optimization results under different driving conditions data sets was used for training, and a multi-model fusion energy distribute strategy under Stacking integrated learning framework was proposed by integrating GRU network and XGBoost algorithm. The simulation results show that compared with the energy storage system using only a single battery, the real-time energy distribution system based on Stacking fusion model can reduce the peak current by 48.7% and 50.8% under UDDS and US06 cycles, respectively, effectively reduces the peak current of the battery and improves the overall performance of the battery.
2024 Vol. 45 (1): 73-81 [Abstract] ( 86 ) HTML (1 KB)  PDF (865 KB)  ( 81 )
82 Research on AC Low Current Calibration Device
TAN Xiangyu,SHAO Haiming,LI Lingzhi,LI Yan,DING Zhiwen
DOI: 10.3969/j.issn.1000-1158.2024.01.12
AC low current calibration is always a difficult problem in AC testing field. The common testing methods in research and production field were analyzed, and the advantages and disadvantages of each method were analyzed. A new method based on AC comparator was put forward, and the AC low current was then traced to mA level alternating current. The calibration device was also developed. By carrying out a series of contrast test, the proposed method extended the measuring capability of alternating current to 1μA (10Hz~10kHz) with the accuracy of 0.05%.
2024 Vol. 45 (1): 82-88 [Abstract] ( 79 ) HTML (1 KB)  PDF (785 KB)  ( 78 )
89 1200kV Lightning Impulse Voltage Standard Measurement System
WANG Kaiyu,ZHAO Wei,LI Chuansheng,CAI Jinhui1,ZHANG Huanghui
DOI: 10.3969/j.issn.1000-1158.2024.01.13
At present, the rated voltage of the national measurement standard system only 700kV, which can't meet the tracing demand of UHV apparatus above 3500kV. A structural analysis is conducted on the developed 1200 kV resistive divider, and performance testing and improvement are carried out on the established 1200 kV impulse voltage measurement system. Comparison and calibration are carried out with the existing 700 kV impulse voltage national standard measurement system within the voltage range of 700kV, and linearity experiments are conducted in the voltage range of 700kV to 1200kV.The evaluation of uncertainty in the calibration of 1200kV standard impulse voltage measurement system is also introduced, the results show that the measurement errors of the test voltage (peak voltage) , front time and time to half-value of the 1200kV lightning impulse voltage standard measuring system are all within the permissible range of the international standard IEC 60060 and the national standard GB/T 16927; the rated voltage level of the national standard measurement system of impulse voltage in our country is raised to 1200kV.
2024 Vol. 45 (1): 89-96 [Abstract] ( 98 ) HTML (1 KB)  PDF (546 KB)  ( 44 )
97 Frequency Tunable Microwave Electric Field Measurement Based on Rubidium Rydberg Atoms
RUAN Weimin,ZHANG Yingyun,FENG Zhigang,ZHOU Yadong,SONG Zhenfei,QU Jifeng
DOI: 10.3969/j.issn.1000-1158.2024.01.14
The continuous tuning measurement of microwave electric field is realized based on the energy level regulation of Rydberg atoms. A rubidium atomic gas chamber is used as a microwave electric field sensor to sense the signal field and the tuning field at the same time. The tuning field is used to fine-tune the Rydberg atomic energy level to realize the synchronous change of the resonant frequency of the signal field, thus expanding the frequency response range of the existing single-frequency microwave measurement. Under the effect of the tuning field that resonates with 68P3/2→66D5/2 transition, the amplitude difference of the measured AT splitting spectrum is used to determine the tuning change of the resonance frequency point of the signal field. Finally, the tuning range of the signal field with the frequency of 6.916GHz is widened from the original 30MHz to 150MHz. It lays a technical foundation for the quantum measurement and application of microwave electric field.
2024 Vol. 45 (1): 97-102 [Abstract] ( 104 ) HTML (1 KB)  PDF (474 KB)  ( 302 )
103 High Precision Near Infrared Fourier Spectrometer for Rapid Measurement of Oil Parameters
FANG Xu,LIU Xin,LI Qi,SHU Hui,ZHANG Zhengdong,CHENG Zhenying,LI Ruijun
DOI: 10.3969/j.issn.1000-1158.2024.01.15
A high precision near infrared Fourier (NIR) spectrometer for rapid measurement of oil parameters was developed to address the need for real time and accuracy in field testing of oil products. To quickly locate the effective signal, the coherent length amplification method was employed by the spectrometer; the Fourier NIR detection optical path was modulated by driving the acquisition control system to interfere at 100nm equal intervals; the final absorption spectrum resolution up to 3.25cm-1 was resolved by the Fourier inversion. The spectrometer was used to test the quality of gasoline samples, and the results showed that the spectrometer can quickly measure the content of five substances in gasoline in a short time, and its maximum volume error does not exceed 0.7%, which can meet the needs of on-site measurement of oil parameters and is of great significance for the supervision of the quality of refined oil products in the market.
2024 Vol. 45 (1): 103-111 [Abstract] ( 87 ) HTML (1 KB)  PDF (746 KB)  ( 186 )
112 Multi-target Vital Sign Detection Based on FMCW Radar
PAN Liang,LIU Kang,ZHANG Yuanhui
DOI: 10.3969/j.issn.1000-1158.2024.01.16
The detection of non-contact human vital signs (such as respiration and heartbeat) based on radar, which has significant importance across various fields. One of these challenges, which the work seeks to solve, is the detection of multiple human targets and the filtering of interference, as well as the elimination of heartbeat signal interference in complex scenarios. To meet this need, a multi-target vital sign detection method, which relies on frequency modulated continuous wave (FMCW) radar, is proposed. After first introducing the radar detection principle and signal model, the entire radar signal processing flow is elucidated, which consists of multi-target distance unit detection, phase extraction, and vital sign signal extraction. In the process of multi-target distance detection, where challenges often arise, an improved Cell Averaging Constant False Alarm Rate (CA-CFAR) algorithm is proposed, a method that not only features adaptive detection thresholds but also solves the problem of repeated distance gate detection near targets in traditional CA-CFAR algorithms, thus achieving multi-target detection. During the vital sign signal extraction process, the Automatic Multi-Scale Peak Detection (AMPD) algorithm is utilized so that breathing and heart rates can be estimated, filtering out invalid peak interferences, which enhances the robustness of heartbeat and respiration rate detection. Finally, through multiple sets of tests, which are conducted to verify the methodology, the average error rates for breathing rate and heart rate detection are found to have reduced by 3.67% and 3.31%, respectively, when compared to commonly used spectral analysis estimation methods, the feasibility and accuracy of the proposed method are validated.
2024 Vol. 45 (1): 112-120 [Abstract] ( 164 ) HTML (1 KB)  PDF (6740 KB)  ( 380 )
121 Research on Gesture Recognition Based on GA-BLS
DU Yihao,CAO Tianfu,FAN Qiang,WANG Xiaoran
DOI: 10.3969/j.issn.1000-1158.2024.01.17
To further improve the accuracy and speed of gesture recognition in the field of human-computer interaction, and explore the influence of muscle fatigue on gesture recognition, an improved GA-BLS method was proposed, genetic algorithms (GA) were used to optimize the parameters of the broad learning system (BLS) model, and elastic network regression was used to improve the traditional BLS model. The proposed model was used to analyze the A-mode ultrasound signal and EMG signal under eight kinds of gestures for gesture recognition, and compared with SVM, KNN, RF, LDA and other methods to verify the effectiveness of the research methods. Furthermore, the A-mode ultrasound and EMG in a long period of time were divided into four data segments. It was found that with the increase of muscle fatigue, the accuracy of gesture recognition showed a significant downward trend, and A-mode ultrasound signal had better fatigue resistance than EMG signal.
2024 Vol. 45 (1): 121-127 [Abstract] ( 92 ) HTML (1 KB)  PDF (731 KB)  ( 107 )
128 Research Progress of Next-Generation Sequencing Reference Materials
LIU Yang,SU Zhaozhong,ZENG Fanjun,YUAN Huijun,ZHANG Yongzhuo
DOI: 10.3969/j.issn.1000-1158.2024.01.18
With the advent of next-generation sequencing technology, gene sequence has been widely studied.Due to the complexity of genetic material, technical errors introduced during sample preparation, sequencing, and analysis, and systematic biases between different sequencing platforms, high-throughput sequencing results suffer in terms of accuracy and consistency across platforms. However, the use of standard materials in the sequencing process can solve these problems. Next-generation sequencing reference materials are usually genetic materials with good characteristics or synthetic reference materials added and simulated electronic data sets. The application of next-generation sequencing reference materials will help calibrate the measurement results of next-generation sequencing and evaluate the instrument performance, which is crucial to ensure the accuracy and consistency of sequencing results.
2024 Vol. 45 (1): 128-134 [Abstract] ( 97 ) HTML (1 KB)  PDF (444 KB)  ( 128 )
135 Functional Network Characterization Analysis of Parkinson’s Mild Cognitive Impairment Based on EEG
LI Xin,ZHANG Qing,ZHANG Ying,XIE Ping,YIN Liyong
DOI: 10.3969/j.issn.1000-1158.2024.01.19
Parkinson’s mild cognitive impairment (PDMCI) is a precursor to dementia in Parkinsons patients, posing challenges for accurate diagnosis using conventional methods such as neurological rating scales and doctors experience. By using the EEG signals of 26 PDMCI patients and 23 normal subjects, the brain function networks of Delta, Theta, Alpha, Beta and Gamma bands were constructed based on the directional transfer function. A novel graph theory feature, efficiency density, is introduced to capture both network density and transmission efficiency. The findings reveal distinctive connectivity patterns, with tighter connections in Delta and Theta bands and sparser connections in Alpha, Beta, and Gamma bands. Significant differences between PD patients and the control group are observed in Theta, Alpha, Beta, and Gamma bands (p<0.05). Therefore, the brain function network can effectively reflect the abnormal brain function status of PD, and the efficiency density characteristic can reflect the characteristic amount of abnormal brain activity in PD.
2024 Vol. 45 (1): 135-144 [Abstract] ( 95 ) HTML (1 KB)  PDF (1140 KB)  ( 206 )
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