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2024 Vol. 45, No. 12
Published: 2024-12-28
 
1745 Study on Fiber Length Standard Device and Correction of Experimental Results
YUAN Weibing,MENG Fei,LIN Baike,YANG Kai,CHEN Liang,FANG Zhanjun
DOI: 10.3969/j.issn.1000-1158.2024.12.01
In order to meet the domestic length metrological requirements of optical time-domain reflectometer (OTDR),a fiber length standard based on the principle of the modulation phase shift technique is realized,which adopts a modular design,including the main system units such as the laser driver,signal modulation,photoelectronic conversion and frequency conversion,as well as the length measurement capability of 1550nm window.By independently measuring the fiber temperature correction coefficient and wavelength correction coefficient the normalized corrections of fiber length changes caused by different temperature and wavelength of the test light source in communication window are realized,compared to other research results of fiber length standard reported in China,as well as a complete uncertainty evaluation,which provide experimental evidences,new ideas and methods for the traceability of fiber length in the field of OTDR calibration.The measurement uncertainties are U=(0.016+7.2×10-6L)m(k=2)at 1310nm,and U=(0.028+7.2×10-6L)m(k=2) at 1550nm respectively.And the uncertainty of calibrating by this standard a 14km fiber used to OTDR transmission standard is 0.13m(k=2),which is twice as good as the original device.
2024 Vol. 45 (12): 1745-1752 [Abstract] ( 26 ) HTML (1 KB)  PDF  (0 KB)  ( 2 )
1753 Joint Angle Error Compensation and Kinematic Calibration of Six-axis Serial Robots
CHEN Lifeng,LIN Junyan,WANG Ling,LIN Jian1,QINA Jiajie,WANG Binrui
DOI: 10.3969/j.issn.1000-1158.2024.12.02
The kinematic calibration of robots is one of the hot research topics in the field of geometric measurement.Existing kinematic calibration methods for serial robots generally overlook the issue of joint angle error compensation.Based on the analysis of experimental data on joint angle errors of a six-axis serial robot, a joint angle error compensation method using Chebyshev polynomial fitting is proposed, followed by the kinematic calibration of the robots body after compensating for the joint angle errors.Subsequently, an experiment is conducted on the ABB IRB 1410 robot using a laser tracker to verify the joint angle error compensation and kinematic calibration.The experimental results show that the proposed method can reduce the mean absolute positioning error of the robot from 2.11mm to 0.66mm.The research provides a theoretical foundation and technical conditions for further improving the positioning accuracy of robots.
2024 Vol. 45 (12): 1753-1761 [Abstract] ( 20 ) HTML (1 KB)  PDF  (0 KB)  ( 1 )
1762 Research on Compensation for Rotary Axis Rotation Error in Single Sensor-based Wafer Calibrator
ZHENG Peng,CHEN Zengyan,TANG Zhichen,RUAN Yujiao,WANG Ruoyu,ZHAO Yan,LIU Tundong
DOI: 10.3969/j.issn.1000-1158.2024.12.03
Compensation for rotational axis error in semiconductor wafer calibrators is crucial for enhancing positioning accuracy.This study presents a compensation method based on a single sensor for the rotational axis error of wafer calibrators.This approach effectively avoids introducing new errors and multiple calibration issues associated with using additional sensors or equipment.The method employs a dual filtering technique that combines ensemble averaging with wavelet threshold denoising to reduce random noise in the collected signals.Additionally, a statistical error separation method is utilized to accurately isolate roundness errors embedded in high signal-to-noise ratio measurements.By employing a multi-step approach, the method calculates precise rotational errors and utilizes the derived error data to correct the circumferential data of the wafer detected by the sensor, thus achieving compensation.Experimental results indicate that the calibration deviation in the positioning of the wafer calibrator is approximately 0.02 mm, demonstrating an improvement in calibration accuracy and validating the effectiveness of the proposed method.
2024 Vol. 45 (12): 1762-1771 [Abstract] ( 11 ) HTML (1 KB)  PDF  (0 KB)  ( 1 )
1772 Research on Vehicle Multi-target Tracking Algorithm Based on UAV Aerial Video
ZHU Qiguang,SHANG Jian,LIU Bo,CEN Qiang,CHEN Weidong
DOI: 10.3969/j.issn.1000-1158.2024.12.04
In order to improve the vehicle multi-target tracking accuracy under the UAV vision platform, a UAV visual vehicle multi-target tracking algorithm that combines the improved YOLOv7 network with the optimized ByteTrack algorithm is proposed. Firstly, in view of the situation where the features of small targets are not obvious, the feature extraction ability of shallow semantic information of the YOLOv7 network is enhanced, and SIoU-Loss is used to optimize the coordinate loss function to speed up the convergence speed of the anchor frame.secondly, according to the vehicle motion characteristics, in based on the ByteTrack algorithm, the state vector of the Kalman filter algorithm is integrated into the acceleration information. finally, the effectiveness of the algorithm is verified on the VisDrone2021 data set. The experimental results indicate that the average detection accuracy of the improved YOLOv7 network is 3.2% higher than the original network, the accuracy of the tracking algorithm is 1.2% higher than the baseline algorithm, and the high-order tracking accuracy is improved by 2.9%.
2024 Vol. 45 (12): 1772-1779 [Abstract] ( 14 ) HTML (1 KB)  PDF  (0 KB)  ( 1 )
1780 Research on the Calibration of Heat Flux Meters Using Guarded Hot Plate Apparatus
SUN Zelong,XU Shuhui,ZHANG Jintao
DOI: 10.3969/j.issn.1000-1158.2024.12.05
The thermal resistance heat flow meter is widely used in the construction industry and industrial energy conservation. However, there is currently no standardized thermal flow measurement standard in China, and there is a lack of standardized heat sources, resulting in poor consistency in the measurement of thermal flow using thermal resistance heat flow meters. The guarded hot plate apparatus has the capability to generate precise and measurable unidirectional heat flow on the measurement plate. The calibration method of two foreign precision heat flow meters and two domestic heat flow meters was investigated using a high-performance single-sample guarded hot plate apparatus developed by National Institute of Metrology of China. A 40mm thick rock wool was used as the thermal resistance insulation material. Three different working conditions were designed: placing the test surface of the heat flow meter close to the measuring plate (Condition 1), placing it in the middle of the rock wool (Condition 2), and attaching it to the cold plate (Condition 3). The sensitivity coefficient C of each heat flow meter was measured. Under Condition 2, the measured value of C showed the smallest deviation from the indications of the two foreign heat flow meters, with a relative deviation of about 7%. The experimental results of all four heat flow meters consistently showed that Condition 2 had the lowest C value, while Condition 1 had the highest. Analysis indicated that the thermal conductivity of the organic solid material constituting the heat flow meter was greater than that of rock wool. Additionally, when in contact with the measuring plate or the cold plate, the resistance of the heat flow passing through the heat flow meter unit was smaller than that passing through the rock wool, resulting in non-unidirectional distribution of the heat flow and uneven distribution of the heat flow on the contact surface, the heat flow meter unit absorbed more heat flow, leading to an overestimation of the C value.
2024 Vol. 45 (12): 1780-1786 [Abstract] ( 15 ) HTML (1 KB)  PDF  (0 KB)  ( 2 )
1787 Research on the Application of A Permanent Surface Single Wellhead Conductance Array Multi-component Measurement Device for Oil Production
KONG Deming,HAO Hu,CHEN Xiaoyu,CHEN Jiliang,WU Peiliang,KONG Weihang,KONG Lingfu
DOI: 10.3969/j.issn.1000-1158.2024.12.06
In order to solve the urgent need and to fill the lack of monitoring devices for oil-gas-water three-phase flow parameters at the surface single wellhead for long-term, stable and reliable use in the field of petroleum production. The numerical simulation model of the developed monitoring device is established by the finite element method,and its structural parameters, electrical characteristics, sensitivity distribution and response characteristics are analyzed and optimized, so as to determine the optimal structure and optimal performance index of the monitoring device. On this basis, a permanent surface single wellhead conductance array multi-component measurement device for oil production(PSSWCAMMD_OP) is developed,and experimental research is carried out on the constructed conductance array multi-component measurement platform. The experimental results show that the measuring device has the characteristics of oil-gas-water three-phase flow conditions such as gas phase flow rate of 5～20m3/d, liquid phase flow rate of 30～70m3/d, and liquid phase water holdup of 70%～90%. Good multi-component measurement performance, multi-component measurement error is less than 3.7%.
2024 Vol. 45 (12): 1787-1796 [Abstract] ( 11 ) HTML (1 KB)  PDF  (0 KB)  ( 1 )
1797 Planar ECT Image Reconstruction Based on 1-bit Compressed Sensing Non Convex Algorithm
TANG Zhihao,ZHANG Lifeng
DOI: 10.3969/j.issn.1000-1158.2024.12.07
In order to improve the imaging quality of planar capacitance imaging system, a planar ECT image reconstruction method based on 1-bit compressed sensing (1-bit CS) non convex algorithm is proposed. Firstly, discrete cosine basis (DCT) is used to sparsely represent grayscale values.Secondly, the maximum minimum concave penalty (MCP) is introduced as the regularization term, and the 1-bit CS MCP regularization model is established. Then, the near end operator of the dual solution is iteratively updated using the MCP non convex algorithm to obtain the optimal dual solution. Finally, calculate the reconstructed grayscale values based on the dual solution and perform image reconstruction. The simulation and experimental results show that compared with Tikhonov algorithm, Landweber algorithm and traditional compressed sensing algorithm, the average relative error and correlation coefficient of the reconstructed image obtained by the proposed method are 0.0496 and 0.9435 respectively, and the average reconstruction time is approximately 0.1723s, which is superior to the other three algorithms. The defect reduction degree and reconstruction speed have been significantly improved.
2024 Vol. 45 (12): 1797-1803 [Abstract] ( 11 ) HTML (1 KB)  PDF  (0 KB)  ( 1 )
1804 Research on L1+p-norm Based Regularization Algorithm forECT Image Reconstruction
MA Min,LIN Conghao
DOI: 10.3969/j.issn.1000-1158.2024.12.08
The regularization method is commonly used for image optimization in ECT. The L1 norm is overly neglecting the image features and the L2 norm is too smooth, which leads to poor imaging quality, an ECT regularization image reconstruction method based on the L1+p norms is proposed. Using the L1+p (0<p<1) paradigm as the regularization term of the loss function, the ECT image reconstruction is made both sparse and smooth by adjusting the value of the parameter p. The simulation experiments results showed that the correlation coefficient of the improved regularization algorithm with norm is on average improved by 77.04% compared with the LBP algorithm, by 36.18% compared with Tikhonov regularization algorithm and by 41% compared L1-norm regularization algorithm in complex multi-bubble flow imaging. Gassolid two-phase flow experiments showed that the proposed algorithm can effectively improve the imaging quality, and is capable of real time adjusting image sparsity.
2024 Vol. 45 (12): 1804-1810 [Abstract] ( 15 ) HTML (1 KB)  PDF  (0 KB)  ( 1 )
1811 Non-intrusive Drainage Pipe Flow Measurement Based on Radar Wave
WU Jing,Lü Jing,LI Xiaoling,LU Ruili
DOI: 10.3969/j.issn.1000-1158.2024.12.09
Based on the principle of continuous wave (CW) radar displacement measurement and the characteristics of strong radar wave penetration, the relationship between liquid level and radar wave intermediate frequency (IF) signal is established on the basis of establishing a relationship model between the propagation path and the radar wave signal strength, and a non-intrusive method of liquid level measurement of water flow in pipelines is proposed. Then the flow rate of water flow in gravity flow drainage pipes is calculated according to Manning formula, and the non-invasive drainage pipe flow measurement based on radar waves is realized. By comparing with the measurement data of the reference electromagnetic flowmeter, the experimental results show that the average error of the proposed non-intrusive flow measurement method is within 3.6%, which can meet the accuracy requirements of the flow measurement of the majority of gravity flow.
2024 Vol. 45 (12): 1811-1817 [Abstract] ( 13 ) HTML (1 KB)  PDF  (0 KB)  ( 1 )
1818 Research on empty-heavy mixing loading matching and measurement algorithm of container trucks in railway freight yards
GONG Xingqi,JIANG Huizeng,LIU Zongdong,AN Aimin,ZHOU Meiling
DOI: 10.3969/j.issn.1000-1158.2024.12.10
To solve the problems of poor real-time matching of heavy containers during train loading in railway freight yards and difficulty in measuring vehicle load deviation, the information from weighing sensors is combined with spatial location information. By using the rising and falling edges of the weighing sensor signal, the loading time and landing point information of the container are determined. When the high-precision positioning signal of Beidou is lost at the time of container landing, the inertial algorithm is used to compensate for the lost landing point information. Finally, by integrating the latitude, longitude, and inertial velocity of the landing points, it is verified that when the distance between the landing points of two containers is about 6000mm, they should be loaded onto the same truck. By calculating the moment balance of the 8 force points on these 2 containers, the unbalanced and heavy load state of the 2 containers can be converted into the vehicle measurement state. By comparing with the data in the railway freight safety platform, the average total weight error is 0.4%, the average lateral bias error is 0.3t, and the average longitudinal offset error is 3.46mm.
2024 Vol. 45 (12): 1818-1823 [Abstract] ( 11 ) HTML (1 KB)  PDF  (0 KB)  ( 1 )
1824 Simulation Mooring Lines Tension Prediction Based onImproved Resnet-LSTM Model
ZHANG Huoming,HUANG Min,LU Pinglan
DOI: 10.3969/j.issn.1000-1158.2024.12.11
The linear and nonlinear forces on an offshore floating platform mooring system in a complex and variable operating environment are predicted, and the number of hidden layers, iterations, and learning rate of the long-short cycle memory (LSTM) single-model prediction network are optimized during the prediction process. A hybrid prediction model with multilayer feature extraction characteristics of variable convolution and wavelet-based activation functions and variable threshold residual shrinkage prediction function is proposed to nonlinearly map the overall forces of the multi-point mooring system in response to the platform motion, analyze the model of multi-point mooring cables, and obtain the value of the mooring cable tension under the combined action of wind and wave currents. The mooring force simulation dataset is trained for prediction using LSTM single model, Resnet-LSTM hybrid model and improved hybrid model. The results show and the network parameters and prediction indicators are optimized, that the prediction accuracy can be as high as 0.9974 using the Resnet-LSTM hybrid model, and the improved Resnet-LSTM prediction using variable convolution is better than the unimproved model. It is demonstrated that the application of the improved hybrid prediction model based on Resnet-LSTM has the effect of improving the network performance in the application of nonlinear time-series feature prediction of tension in multipoint mooring systems.
2024 Vol. 45 (12): 1824-1831 [Abstract] ( 13 ) HTML (1 KB)  PDF  (0 KB)  ( 1 )
1832 Research on Fault Diagnosis of Rolling Bearing Based on MPGCN-Resnet
YAN Shengli,FU Hui,LI Hao
DOI: 10.3969/j.issn.1000-1158.2024.12.12
Rolling bearings are installed in various machine tools and other production machinery,and are prone to faults and failures,requiring continuous monitoring to ensure their safe and reliable operation.Therefore,a multiple parallel graphs convolutional neural residual networks (MPGCN-Resnet) is designed to complete the fault diagnosis of rolling bearings.MPGCN-Resnet consists of four parts in total.Among them,the time-frequency graph acquisition part based on cmor wavelet can complete refined processing of reconstruction and disassembly in various fault vibration signals.The feature acquisition part based on a multi-parallel network can improve generalization and accelerate convergence.The feature learning part under the residual structure graph neural network can utilize the residual structure to complete feature learning and can realize the in-depth exploration of fault characteristics of rolling bearings.The GAP-Softmax fault classification part can complete the effective diagnosis of rolling bearing faults.Comparative and analytical experiments are conducted on the accuracy and loss values of MPGCN-Resnet,IHDSVM-Alexnet and MSATM method under varying operating conditions and noise levels using the CWRU bearing dataset.The results show that the average fault diagnosis accuracy of MPGCN-Resnet for rolling bearings can reach 96.4%,which is higher than 91% in a -6 dB noise environment and greater than 90% when the load suddenly changes by 3×0.75kW.MPGCN-Resnet has higher fault diagnosis accuracy for rolling bearings in various variable working conditions and variable noise environments than the other two methods,and can alleviate the problems of increased parameters and excessive calculation.
2024 Vol. 45 (12): 1832-1840 [Abstract] ( 10 ) HTML (1 KB)  PDF  (0 KB)  ( 1 )
1841 Noise Characteristic Study of 2.2 MW Large Wind Turbine Based on Hilbert-Huang Transform
HE Jie,ZHANG Shiwei,SUN Bingchuan,XUE Minghua,SU Mingxu
DOI: 10.3969/j.issn.1000-1158.2024.12.13
To measure the aerodynamic noise of a 2.2 MW horizontal-axis wind turbine,six measurement points were set up in a large wind farm.The points were placed in the upwind,downwind,and at a 60° angle around the turbine.The trends of total sound pressure level(TSPL) of measurement points were obtained by 1/3 octave analysis under the wind speeds ranging from 6.55～15.00m/s.On the basis,the empirical modal decomposition(EMD) and Hilbert-Huang transform(HHT),combined with the marginal spectra,were applied to obtain the key time-frequency characteristics of wind turbine noise.The results showed that the total sound pressure levels at the 60° measurement points are similar to those of the standard measurement points in the same direction.However,the noise level at measurement point 4#,located upwind of the wind turbine,is relatively lower.The variance contribution ratio and correlation coefficient derived from the EMD reveal that the primary energy of the noise is concentrated in the frequency band of 770~1120Hz.The principal frequency of the fitted marginal spectrum is in good agreement with the cubic relationship of the corresponding wind speed.
2024 Vol. 45 (12): 1841-1848 [Abstract] ( 12 ) HTML (1 KB)  PDF  (0 KB)  ( 1 )
1849 Study on Sound Pressure Measurement Based on Photon Auto-correlation Method
LU Tao,LIU Jilong,ZHU Weimin,QI Fang
DOI: 10.3969/j.issn.1000-1158.2024.12.14
In order to solve the problem that the correlation delay time τ of the traditional autocorrelator-based experimental system is too large when detecting the air free-field sound pressure, an anechoic box environment was built, a non-fixed-frequency-shift optical system, and a signal acquisition and processing system were designed for detecting the air free-field sound pressure based on the photon correlation method.The method decreased the step value of autocorrelation delay time (τ) to 1μs, reducing the measurement error of sound pressure by 0.2dB compared to traditional autocorrelator-based experimental systems.Finally, a comparison with the microphone method and the conventional photon autocorrelation method was made, and the results of the measurement of 106.4dB sound pressure in the range of 600~1200Hz showed that the maximum deviation of the proposed method for the measurement of the sound pressure in the air sound field was 0.6dB.
2024 Vol. 45 (12): 1849-1854 [Abstract] ( 13 ) HTML (1 KB)  PDF  (0 KB)  ( 2 )
1855 Development of an on-chip Power Divider for the Quantum Voltage Chip
LI Xiaoyu,XU Sisi,CHENG Qianshuo,ZHONG Yuan,CAO Wenhui,LI Jinjin
DOI: 10.3969/j.issn.1000-1158.2024.12.15
Using the power divider in the quantum voltage chip is one of the most important methods to improve the quantum output amplitude of the quantum chip. The π-type LC circuit can achieve a small on-chip Wilkinson power divider, and add a λ/4 converter to broaden the working bandwidth. Developing an on-chip broadband Wilkinson power divider based on the design simulation. In the range of 13GHz to 23GHz, the power allocation is given in (3.0±0.25)dB. In the range of 12GHz to 23GHz, its input and output reflections are respectively below -12dB and -10.5dB. In the range of 1.5GHz to 30GHz, three arrays with power divider are irradiated by microwave. The test result shows that the three Josephson junction arrays are the same, proving that the power divider can effectively achieve two-way equal output.
2024 Vol. 45 (12): 1855-1861 [Abstract] ( 17 ) HTML (1 KB)  PDF  (0 KB)  ( 1 )
1862 Dual-band Resonant Complex Permittivity Sensor Based on Interdigital Capacitor Structure
DU Minghe,WANG Zeyu,YUAN Haoyun,SHAO Linxiang,FANG Lili,BAO Xiue
DOI: 10.3969/j.issn.1000-1158.2024.12.16
A dual-frequency resonant sensor is designed based on the interdigital capacitance structure to measure the complex permittivity of liquid.The advantages of the sensor in sensitivity,miniaturization and operating bandwidth are verified by simulation analysis,machining and measurement.The results of simulation and measurement show that the sensitivity of the dual-band resonant sensor is as high as 5.2%,which can realize the nondestructive measurement of the complex permittivity of the liquid at two frequency points with a very small amount of liquid at the same time,and can measure the concentration of methanol-ethanol mixed solution based on certain calibration operations.The measurement error of liquid complex permittivity is reduced from 4.2% to 2% by obtaining the test data of two frequency points simultaneously.In addition,the structure size of the interdigital capacitor can be further adjusted to develop a multi-band resonant sensor to achieve accurate acquisition of the wide-band dielectric spectrum of the liquid.
2024 Vol. 45 (12): 1862-1867 [Abstract] ( 13 ) HTML (1 KB)  PDF  (0 KB)  ( 1 )
1868 Identification of Synchronous Motor Parameters Using Multi-link Improvement Harris Hawks Optimization
LIAO Zhenglin,SHEN Yanxia
DOI: 10.3969/j.issn.1000-1158.2024.12.17
Aiming at the problems of the traditional methods in the field of parameter identification of permanent magnet synchronous motor (PMSM),it is difficult to identify multiple parameters at the same time and the identification accuracy is not high enough,parameter identification algorithm is proposed,in which the Harris Eagle optimization algorithm is adopted.In order to improve the accuracy and stability of the identification algorithm,this thesis improves the Harris Eagle algorithm from three aspects:First,the position of the eagle colony is initialized by introducing Logistic chaotic mapping from the direction of population initialization,increasing the diversity of the population and speeding up the convergence of the identification algorithm.Secondly,from the perspective of eagle position update,the random reverse learning strategy is used to optimize the worst position individual in the eagle group,so as to improve the fuzziness and randomness of the algorithm,enhance the global search performance,and make the identification results more accurate.Finally,in order to prevent premature convergence,the current optimal individual position is retained into the next iteration to improve the problem that the traditional Harris Eagle algorithm is prone to local optimization and precision decline.On the basis of the mathematical model based on PMSM voltage equation,MIHHO algorithm and standard Harris Eagle algorithm (HHO),particle swarm optimization (PSO) and Sparrow search algorithm (SSA) are tested.The results show that MIHHO algorithm has better stability,convergence speed and higher identification accuracy for PMSM parameter identification.
2024 Vol. 45 (12): 1868-1875 [Abstract] ( 12 ) HTML (1 KB)  PDF  (0 KB)  ( 1 )
1876 Traffic Signal Control Based on Improved Chaotic Particle Swarm Algorithm
WU Peng,YE Baolin,WU Weimin,CHEN Bin,ZHANG Yijia
DOI: 10.3969/j.issn.1000-1158.2024.12.18
Due to the limited global search capability,traffic signal control (TSC) methods based on traditional particle swarm optimization (PSO) algorithms are prone to falling into local optima.In addition,the TSC model with a fixed signal cycle lacks flexibility in dealing with complex traffic flows that change over time.To address these issues,a TSC method based on an improved chaotic particle swarm optimization (ICPSO) algorithm is proposed,which utilizes chaotic motion to enhance global search capabilities to overcome local optima.The proposed ICPSO algorithm introduces a neighborhood radius parameter for elite particles with higher fitness in the population,implements neighborhood chaos search,and retains the advantageous characteristics of particles while improving their ability to escape local optima.In addition,a variable-period TSC model (VTSC) is designed to dynamically adjust the signal cycle length based on time-varying traffic flow,in order to flexibly respond to complex traffic conditions.In order to evaluate the performance of the proposed method,simulation experiments are conducted in the VISSIM simulation environment.The experimental results show that compared with the baseline method,the proposed method reduces the average queue length by 9.34% and the maximum queue length by 15.28%,and reduces the average delay time by 9.45% and the average number of stops by 5%. 
2024 Vol. 45 (12): 1876-1884 [Abstract] ( 14 ) HTML (1 KB)  PDF  (0 KB)  ( 1 )
1885 Small Cesium Atomic Fountain Clock for Time Keeping System
JIN Shuanghao,LIN Pingwei,RU Ning,MA Yanning,JIANG Wensong,LUO Zai
DOI: 10.3969/j.issn.1000-1158.2024.12.19
The small cesium atomic fountain clock has excellent long-term stability performance,and has the advantages of high reliability,automation,miniaturization and mobility.It has the potential to be realized as a mobile timekeeping clock in a vehicle-mounted form.It can be used as a node clock in a timekeeping atomic clock group to ensure accurate frequency and time signals.The developed small cesium atomic fountain clock NIM-TF3 has a frequency stability of 2.7×10-13@s and 5.3×10-15@one day.NIM-TF3 adopts an integrated laser system and integrated electronic control system,which can achieve long-term automatic continuous operation.It integrates the developed small microwave frequency synthesizer with the physical system,which significantly reduces the system volume and enhances the overall stability.and reliability.In addition,through evaluation,it was found that the second-order Zeeman relative frequency shift caused by uneven distribution of the C field is 7.3×10-14,and the uncertainty is 0.2×10-15.The overall volume of NIM-TF3 is less than 0.7m3,and it has the potential to become a vehicle-mounted fountain clock.
2024 Vol. 45 (12): 1885-1891 [Abstract] ( 410 ) HTML (1 KB)  PDF  (0 KB)  ( 58 )
1892 Study on Tube Voltage Value Transfer Technology of Medical Breast X-ray Machine
REN Guoyue,GUO Siming,QIN Feng,MA Boxuan
DOI: 10.3969/j.issn.1000-1158.2024.12.20
With the continuous improvement of the diagnostic X-ray quality evaluation system, tube voltage has become the important index for evaluating the quality of X-ray radiation beams . The measurement method and traceability method of medical breast tube voltage are mainly studied. Two methods are used to measure the tube voltage, namely the voltage divider box voltage division method and the energy spectrum endpoint method.The measurement results are quantitatively transmitted to several semiconductor detectors commonly used in the market. The experimental results show that the maximum difference between the two methods of tube voltage measurement is within 1.0%,the results of measuring the tube voltage using the above two methods have been verified to be reliable. The voltage measurement results of four semiconductor detector tubes commonly used in the domestic market are calibrated, and the deviation of the relative inherent error is within 2.0%, which can be used for on-site quality control of medical breast machines.
2024 Vol. 45 (12): 1892-1899 [Abstract] ( 6 ) HTML (1 KB)  PDF  (0 KB)  ( 1 )
1900 Surface Electromyography Gesture Recognition Based on Personalized Feature Analysis
LIU Dongbo,LIU Yun,FANG Yu,YI Minsheng,WANG Weibo
DOI: 10.3969/j.issn.1000-1158.2024.12.21
To realize artificial limb control, it is an important method to use surface electromyography (sEMG) signal to recognize gestures. sEMG signals are electromyographic signals collected from the surface layer of the skin, which can reflect the neuromuscular activities to a certain extent. Due to its random and non-smooth characteristics, the use of sEMG signals to control artificial intelligent prosthetic limbs has never been able to achieve the desired results, especially reflected in the influence of individual differences such as gender. A gesture recognition method based on surface EMG signals is proposed for seven types of gesture movements through differentiated gender characterization. Experimental results show that the recognition accuracy of the method is significantly improved in all five classifiers. Among them, linear discriminant analysis has the most significant improvement, reaching 15.84%; support vector machine and extreme gradient boosting are the most effective in gesture recognition, with an accuracy of 98.41%.
2024 Vol. 45 (12): 1900-1908 [Abstract] ( 14 ) HTML (1 KB)  PDF  (0 KB)  ( 1 )
1909 Non-SI Units in the SI and their Use with SI Prefixes
Richard J C Brown，译者 曹晶,任思源,于连超
DOI: 10.3969/j.issn.1000-1158.2024.12.22
The International System of Units (SI) is one of the greatest scientific, technological, and political achievements of recent times. After the formal introduction of the SI, it was necessary to accept the ongoing usage of some non-SI units because of their long history of previous use, despite this losing the benefit of coherence that the SI brings. This work reviews the history of non-SI units that have been allowed for use with the SI in successive SI Brochures, observes the rules that have been required for this use especially with SI prefixes, and notes that this set of non-SI units has decreased significantly as the SI has become more deeply embedded in modern society. The current situation, where a relatively small set of non-SI units remain accepted for use with the SI, is analyzed. It is observed that these non-SI units acquire quasi-SI status because of their listing in the SI Brochure. As a result, it is proposed that this set of non-SI units should be as small as possible and that clear rules for their use are necessary, most obviously with SI prefixes where the current guidance needs improvement. Historical precedent has been examined to assist in shaping these recommendations, which could be discussed and considered when the SI Brochure is next updated.
2024 Vol. 45 (12): 1909-1916 [Abstract] ( 13 ) HTML (1 KB)  PDF  (0 KB)  ( 1 )
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