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2024 Vol. 45, No. 11
Published: 2024-11-28
 
1585 Power Measurement System Referenced to the Pulse-driven AC Josephson Voltage Standard
LU Qiliang,ZHOU Kunli,HAN Qina,SHI Yang,ZHAO Jianting,YANG Yan,XU Lei,LU Yunfeng,HUANG Lu,ZHAI Changwei,QU Jifeng
DOI: 10.3969/j.issn.1000-1158.2024.11.01
An AC power measurement system based on the pulse-driven AC Josephson voltage standard is developed. By using a precision inductive voltage divider, two-stage current transformers and a sampling resistor, the system converts the voltage and current of AC power into two AC voltages within 1V. They are referenced to two pulse-driven AC Josephson voltage standards. The phase difference between two AC voltages is obtained with complex ratio measurement. The phase difference between the voltage and current of the AC power source is achieved by phase difference correction. This system needs only one set of voltage comparison module and has a simpler structure compared to state-of-the-art system structures. Under the conditions of voltage equal to 220V, current equal to 1A, frequency equal to 60Hz and power factor equal to 1.0, the uncertainty is 5.6μW/VA (k=2). The results are consistent with the results provided by a standard power meter.The mentioned study provides supports for establishing a new generation of AC power standards referenced to the pulse-driven AC Josephson voltage standard.
2024 Vol. 45 (11): 1585-1592 [Abstract] ( 107 ) HTML (1 KB)  PDF (672 KB)  ( 6 )
1593 Research on the Measurement of DC High Voltage Dividers Based on Improved Voltage Summation
LIU Fangming,LIU Hao,LI Dengyun,XIAO Kai,DU Baiwen
DOI: 10.3969/j.issn.1000-1158.2024.11.02
DC high voltage dividers was usually calibrated by the method of resistance or leakage current mesurement. The 100kV and below dividers voltage ratio was measured by resistance measurement,as leakage current could be ignored because of its little order of magnitude.And the leakage current measurement method was used in the dividers with resistance-measurement-layer-only structure.Voltage summation was applied in DC high voltage dividers measurement. The improved voltage summation mathematical model was built based on the new low-voltage side resistance out-put technology.An experiment was carried out on a 100kV DC divider, and normalized deviation method was used in the voltage summation experiment result evaluation. The experiment shows that the component uncertainty of improved voltage summation is 10-5～10-6, and the 100kV DC divider uncetainty is 1.3×10-5 (k=2).
2024 Vol. 45 (11): 1593-1600 [Abstract] ( 64 ) HTML (1 KB)  PDF (519 KB)  ( 4 )
1601 Error Measurement Method of 15～30Hz Low Frequency Transformer Based on Improved Digital Comparison Method
XIONG Bo,LIU Hao,ZHOU Feng,LI He,HUANG Tianchao
DOI: 10.3969/j.issn.1000-1158.2024.11.03
To presents a comprehensive study on error calibration technology for low frequency instrument transformers test set, aiming to achieve high accuracy measurements. Firstly, the low frequency error linearity of the A/D channel in the data acquisition board is analyzed and tested. To address the low frequency error in the sampling data points, a dynamic compensation method is proposed. Additionally, the channel gain error is eliminated using the sampling sequence reconstruction method. An optimal adaptation ratio between the sampling frequency and signal frequency is designed, along with an optimization algorithm for low-frequency signal data processing, significantly improving the measurement accuracy of low-frequency instrument transformers test set. The test results demonstrate a remarkable improve in measurement uncertainties, with ratio difference and phase difference reduced to 10×10-6(10μrad) for different input ratios and frequencies.
2024 Vol. 45 (11): 1601-1606 [Abstract] ( 46 ) HTML (1 KB)  PDF (616 KB)  ( 4 )
1607 Tailings Pond Dry Beach Length Measurement Based on Deep Learning Water Instance Segmentation
SUN Yeqing,CHEN Hongfei,TONG Renyuan
DOI: 10.3969/j.issn.1000-1158.2024.11.04
A method based on YOLOv8 for water instance segmentation has been proposed, achieving rapid, efficient, and accurate measurement of the dry beach length of tailings ponds under real-time video streams. Firstly, a high-quality water instance segmentation COCO dataset is completed. Secondly, mainstream deep learning instance segmentation algorithms are analyzed, and the YOLOv8 model is chosen to efficiently recognize the waterline and output image coordinates. Finally, the internal and external parameters of the camera are calibrated. By applying the principles of camera imaging and installing surveillance cameras at the end of the tailings pond, the dry beach length is predicted. Experiments prove that this model can not only accurately predict the dry beach length but also has good stability in segmenting the water boundaries of different tailings ponds. It has a good effect on non-contact measurement in the field under real-time video stream mode, with an error controlled within 2%.
2024 Vol. 45 (11): 1607-1614 [Abstract] ( 43 ) HTML (1 KB)  PDF (840 KB)  ( 4 )
1615 Research on the Separation and Noise Reduction Method of Spindle Radial Rotation Error Based on LSTM-GRU Neural Network
CHI Yulun,LI Ximing,ZHU Wenbo,YU Jianhua
DOI: 10.3969/j.issn.1000-1158.2024.11.05
The frequency domain three-probe method is a common method for separating spindle rotation errors. Its error separation accuracy is greatly affected by the noise in the measured signal. Inappropriate noise reduction methods will distort the test results. To this end, a spindle rotation error separation and noise reduction method based on LSTM-GRU neural network is proposed.First, a test system is built using the optimized sensor angle by genetic algorithms and the spindle rotation error signal is acquired.Then, the Kalman filter is configured to reduce the noise of the three sensor signals, the synchronous rotation error and asynchronous rotation error are separated by the three-probe method in frequency domain.Finally, the LSTM-GRU model is used to reduce the noise of synchronous and asynchronous rotation error respectively.The noise reduction results of the LSTM-GRU model are compared with the results of LSTM-LSTM model、Kalman filtering and Wavelet threshold denoise methods.The Allan variance is calculated to evaluate the noise reduction effect of different methods.The experimental result shows that after noise reduction using the LSTM-GRU model, the Allan variance of the synchronous rotation error is 2.014×10-8mm2 and the Allan variance of the asynchronous rotation error is 3.967×10-8mm2, which are both less than the results of Kalman filtering and Wavelet threshold noise reduction.The noise reduction effect of the LSTM-GRU model is optimal.The asynchronous rotation error of the spindle at the test speed of 6000r/min is 2.42μm and the asynchronous rotation error is 3.21μm, which meets the actual situation.
2024 Vol. 45 (11): 1615-1625 [Abstract] ( 38 ) HTML (1 KB)  PDF (975 KB)  ( 3 )
1626 Road Object Detection in Foggy Weather Based on Polarization Imaging and YOLOv8
TAN Ailing, LI Xiaohang,ZHAO Yong,GAO Meijing,SU Haijie,LIU Chuang,GUO Tianan
DOI: 10.3969/j.issn.1000-1158.2024.11.06
Detection of automobile and pedestrian targets in foggy weather is of interest to the field of autonomous driving. Polarized images at 0°, 45°, 90°, and 135° were first acquired by a polarization imaging device, then I04590, stokes, and pauli image datasets were constructed through three different fusion methods. An improved YOLOv8 object detection algorithm was proposed to improve the detection accuracy of two types of targets, automobiles and pedestrians, in polarized images in foggy weathers. A MixSPPF structure based on hybrid pooling was proposed to improve the original SPPF structures ability to extract global information. Then a Multi-scale Module was designed based on convolutions of different sizes and combined with the Coordinate Attention mechanism to enhance the extraction of spatial and channel information. The experimental results showed that the proposed improved YOLOv8 algorithm achieved the mean average precision (mAP)is mAP@0.5 value of 83.4% and mAP@0.50.95 value of 39.3%, which were improved by 1.6% and 0.9% respectively compared to the original YOLOv8 algorithm.
2024 Vol. 45 (11): 1626-1633 [Abstract] ( 38 ) HTML (1 KB)  PDF (710 KB)  ( 4 )
1634 Face Alignment in Thermal Infrared Images Based on Inverted Residual Multi-scale Convolutional Attention
LIU Xulong,LI Xiao,XU Shuang,JIA Ziwei
DOI: 10.3969/j.issn.1000-1158.2024.11.07
Face alignment in thermal infrared images is crucial for accurately extracting facial temperature data, as its positioning precision directly impacts the accuracy of temperature analysis in various facial regions. However, most prevalent face alignment algorithms designed for visible face images encounter limitations when directly applied to infrared thermal images, resulting in insufficient accuracy. To address this issue, a face alignment algorithm specifically designed for thermal infrared images, leveraging a multi-scale convolution attention mechanism, is introduced. This algorithm effectively integrates the multi-scale convolutional attention mechanism with an inverted residual convolutional network, while incorporating the wing loss as the loss function to further enhance the network models feature extraction capabilities. On both an open thermal infrared face dataset and a self-collected facial palsy dataset, the algorithm achieves normalized mean errors of 3.23% and 3.94%, respectively. This represents a significant improvement in localization accuracy for facial features compared to traditional methods, extending its applicability to populations with facial palsy. This advancement holds immense potential for various applications.
2024 Vol. 45 (11): 1634-1641 [Abstract] ( 44 ) HTML (1 KB)  PDF (703 KB)  ( 2 )
1642 Image Analysis Method of Sand and Soil Particle Gradation Based on Mean Sampling Principle
SHANG Fulei,LIAN Jifeng,LI Xiaoning,LIU Yu,LEI Zhijie,HU Yaozhong
DOI: 10.3969/j.issn.1000-1158.2024.11.08
Particle grading is one of the key parameters affecting the mechanical properties of roadbed fill. The traditional sieving method is difficult to refine and quickly determine the sandy soil particle group due to the large interval between sieve diameters. A new method for estimating the sandy soil particle gradation based on image scanning and mean sampling technology is proposed. The method is based on the scanning electron microscope(SEM) and image processing software ImageJ joint testing technology to determine the geometric parameters of the sand particle morphology. The difference in the distance between any two parallel tangent lines of irregular particles on the projected image contour, namely the Feret diameter as the equivalent diameter of an ideal sphere is discussed, and the equivalent area and volume equations for a single sand particle are established. Based on the general rule that the relative density of sand particles gradually increases with the decrease of particle size, a negative power function model between sand particle size and relative density is fitted, and a function expression for the mass and particle size of a single sand particle is established. Finally, the accuracy of the arithmetic mean method and mean sampling method for sand particle grading is examined by sieving method. The results show that the relative error of ImageJ in identifying sandy soil particles of millimeter level and below depends on the difference between particle size and scale length, that is, when the particle size is smaller than the scale length, the larger the difference, the lower the measurement accuracy. When the particle size approaches or exceeds the length of the scale, the measurement accuracy is higher and more stable. The arithmetic mean method shows strong randomness and is not suitable as a basis for determining the grading parameters of sand particles. The grading curve of sandy soil particles obtained by the mean sampling method with short diameter is the most consistent with the results of the sieve method, which can be used for the estimation of sandy soil particles grading parameters, followed by average diameter, long diameter. The new method can arbitrarily divide sand particle groups and obtain relatively accurate grading parameters, with reliable results and convenient operation.
2024 Vol. 45 (11): 1642-1653 [Abstract] ( 48 ) HTML (1 KB)  PDF (916 KB)  ( 6 )
1654 Accuracy Analysis of Refraction Error Correction Models in Three-axis Photogrammetry
ZHANG Bo,MU Chunmei,PAN Qiang,LI Yanxia1,YANG Jin
DOI: 10.3969/j.issn.1000-1158.2024.11.09
Photogrammetric technique applied to triaxial test can realize the non-contact measurement of soil sample deformation, however the measurement accuracy of the method is susceptible to the refraction influence of different media. To solve the problem, firstly, the photogrammetric method is verified to have high measurement accuracy without the influence of refraction by measuring the distance of the plane artificial coding points and the axial and radial lengths of the rigid cylinders in air; but the light will be affected by the refraction of different mediums, such as the air, the organic glass cover and water in the pressure chamber, which results in a large measurement error. In order to eliminate the effect of refraction, the three-dimensional refraction error correction model is applied to the triaxial test of saturated mixed soil, and the test results are analyzed for accuracy from axial and radial directions. The test results show that:1) the effect of refraction amplification on the axial measurement accuracy of triaxial soil samples is very small and negligible, but the effect on the radial measurement is larger, which needs to be corrected by the refraction error; 2) after the error correction, the absolute and relative errors of the radial measurements of triaxial soil samples are 0.120mm and 0.59%, respectively, indicating that the refraction error correction model can improve the accuracy of triaxial photogrammetry.
2024 Vol. 45 (11): 1654-1664 [Abstract] ( 39 ) HTML (1 KB)  PDF (827 KB)  ( 0 )
1665 Lightweight Target Detection Method Based on Adaptive Feature Fusion of Optimized RetinaNet
ZHANG Liguo, JI Xinye, ZHANG Yupeng, GENG Xingshuo, ZHANG Sheng
DOI: 10.3969/j.issn.1000-1158.2024.11.10
Aiming at the problems of large amount of computation and complex model in target detection algorithm, which make it difficult to deploy in application scenarios with limited computing resources on embedded platform. The lightweight target detection method based on optimized RetinaNet is proposed with adaptive feature fusion. Firstly, the proposed algorithm refers to the Ghost Module in GhostNet to reduce the number of model parameters. By means of a spatial feature fusion mechanism, the scale invariance of features is improved. Secondly, the idea of structural reparameterization is integrated to increase the depth of training, realize multi-branch training, single-branch training, and better improve the detecting performance of the model. The method is evaluated on two common target detection datasets, PASCAL VOC2007 and COCO. With an average accuracy of 54.1%, better than that of RetinaNet. The experimental results show that the memory taken by the proposed method is 170.71MByte, which is 44.27% of the memory taken by the RetinaNet, indicating that the proposed algorithm can greatly improve the network inference speed without ensuring the accuracy.
2024 Vol. 45 (11): 1665-1670 [Abstract] ( 47 ) HTML (1 KB)  PDF (450 KB)  ( 6 )
1671 Strip Surface Defect Detection Based on Improved YOLOv5
YANG Wei,YANG Jun,XU Congyuan
DOI: 10.3969/j.issn.1000-1158.2024.11.11
Aiming at the problems of low detection accuracy and slow detection speed in strip surface defect detection methods, a strip surface defect detection method based on improved YOLOv5 is proposed. Firstly, the Content-Aware ReAssembly of FEatures (CARAFE) is used as the upsampling operator of multi-scale feature fusion, and the Channel Scaling-Adaptively Spatial Feature Fusion (CS-ASFF) is constructed to enhance multi-scale feature fusion and control model complexity. Secondly, the GSConv and VoVGSCSP modules are introduced into the convolutional layer and cross-layer structure of the model to reduce computation and improve detection accuracy. Finally, the Focal-GIOU Loss is used as the loss function to solve the problem of imbalance between difficult and easy samples in strip defect images, thereby improving the adaptability to complex data. Experimental results show that the method achieves 80.6% mean average precision (PmAP) on NEU-DET dataset, with a calculation amount of 14.8 GFLOPs. Compared with YOLOv5, PmAP is increased by 4.3% and the computation amount is reduced by 6.33%. Compared with the current mainstream object detection networks, this method has the highest detection accuracy with a lower calculation amount and can meet the real-time detection of surface defects on steel strips in real industrial scenarios.
2024 Vol. 45 (11): 1671-1680 [Abstract] ( 47 ) HTML (1 KB)  PDF (893 KB)  ( 4 )
1681 Analysis of Gas-liquid Two-phase Flow CharacteristicsBased on Multivariate Multi-scale Dispersion Entropy
WU Chuanbao,ZHANG Lifeng
DOI: 10.3969/j.issn.1000-1158.2024.11.12
The method for analyzing the flow characteristics of gas-liquid two-phase flow in vertical pipelines based on multivariate multi-scale dispersion entropy is presented. Flow pattern information of gas-liquid two-phase flow in a vertical upward pipeline is obtained using a conductivity array sensor. The dimensionality of the collected high-dimensional time series is reduced by the principal component analysis (PCA) method. Then, multivariate multiscale dispersion entropy (mvMDE) is adopted to measure the complexity of multivariate time series with different flow patterns, and compared with multiscale dispersion entropy (MDE) used for univariate time series. Further, calculate the average value of the first 10 scales of mvMDE and the growth rate of the first 5 scales. The results show that mvMDE corresponding to the same flow pattern had greater differences, and mvMDE is more sensitive to flow pattern transition. Therefore, mvMDE can more effectively reveal the evolution process of two-phase flow from bubble to slug. From the aggregation of bubbles to the gradual collapse of air plugs, from the appearance of pseudo-periods to their decline, they can all be reflected by the changes in entropy, and the joint distribution of the average value and growth rate can effectively realize flow pattern identification.
2024 Vol. 45 (11): 1681-1687 [Abstract] ( 45 ) HTML (1 KB)  PDF (654 KB)  ( 4 )
1688 Research on Calibration Technology of ReciprocalMagnetoelectric Vibration Sensor
LIAN Xiangkun,CAI Chenguang,KONG Ming,LIU Zhihua,Lü Siyao
DOI: 10.3969/j.issn.1000-1158.2024.11.13
A new reciprocity calibration method for passive servo vibration sensors is proposed. This method is based on the basic principle of reciprocity calibration. According to the dual coil characteristics of passive servo vibration sensors, they are divided into calibrated sensors and reciprocal sensors. By establishing the vibration differential equation, the frequency response characteristics of the sensitivity ratio, sensitivity product, and reciprocity calibration coefficient of the two sensors are analyzed, and the corresponding calibration method is finally proposed. Based on this method, two experimental measurements are carried out to obtain the sensitivity ratio and sensitivity product, and combined with the reciprocal calibration coefficients, the calibration of passive servo vibration sensors is realized. And the experimental comparison with the laser interferometric method is carried out, and the experimental results show that the relative error of the calibration results of the two sensors is no more than 1% at the frequency of 1~100Hz.
2024 Vol. 45 (11): 1688-1694 [Abstract] ( 53 ) HTML (1 KB)  PDF (536 KB)  ( 4 )
1695 Research on Automated Calibration of Hydraulic Piston Gauges
WANG Bowen,YANG Yuanchao,PANG Guibing,MA Kun,YUE Jin,HUANG Qian
DOI: 10.3969/j.issn.1000-1158.2024.11.14
Using a high-resolution pressure transducer, an automated calibration system for hydraulic piston gauges in the range of 1~120 MPa has been developed based on the theoretical analysis, manifold design and programming. The transducers' linear coefficients and its long-term stability were tested, and the results showed that the deviations of linear coefficients from 1 were less than ±4×10-4. Comparing with the traditional calibration method, the reliability of the developed system for the dissemination of pressure SI-unit from the NIM primary pressure standard has been demonstrated. The calibration results by two methods, the so-called Δp-method and p-method, were compared using the automated system, and the consistency of the two methods was verified. By using the automated system for the calibration of hydraulic piston gauges, the relative expanded uncertainty of the calibrated effective area is 32×10-6 (k=2), and the expanded uncertainty of the calibrated distortion coefficient is 1.8×10-7 /MPa(k=2). The time required for calibration is significantly reduced compared to traditional methods.
2024 Vol. 45 (11): 1695-1701 [Abstract] ( 45 ) HTML (1 KB)  PDF (494 KB)  ( 5 )
1702 Research on Identification Method of Dynamic SensitivityCoefficient of Force Transducer
LIU Jingjing,JIANG Wensong,LUO Zai,WANG Yanqing,YIN Xiao
DOI: 10.3969/j.issn.1000-1158.2024.11.15
To reduce the large measurement error caused by the weak nonlinear time-varying characteristics of sensitive materials during dynamic measurement, an identification method of dynamic sensitivity coefficient of force transducer is proposed. First, the kernel function matrix of the calibrated force transducer is obtained at different excitation frequencies; second, the singular value of kernel function matrix is modified by regularization method, and the identification model of dynamic sensitivity coefficient matrix is established. To verify the accuracy of the method, a sinusoidal force calibration device is used to calibrate the force transducer dynamically, and its dynamic sensitivity coefficient is identified. The experimental results show that the mean relative error of the identification method is 7.05%, and the standard deviation of arithmetic mean is 1.18, which are reduced by 65.86% and 88.00% compared with the traditional method. In all, this method can improve the dynamic performance of the calibrated force transducer.
2024 Vol. 45 (11): 1702-1708 [Abstract] ( 52 ) HTML (1 KB)  PDF (667 KB)  ( 4 )
1709 Hydrostatic Excitation Hydrophone Calibration Based on Motion Trajectory Constraints
WANG Yixin,WANG Ke,WANG Min,XING Guangzhen,YANG Ping,ZHENG Huifeng
DOI: 10.3969/j.issn.1000-1158.2024.11.16
In the traditional hydrostatic excitation method for hydrophone calibration system, the influence of inertial force on equivalent sound pressure is inconsistent due to the lack of constraint of the connecting hose during water vibration in the connecting hose, resulting in a large uncertainty introduced by measurement repeatability,which affects the uncertainty of hydrophone sensitivity calibration. A hydrostatic excitation method for hydrophone calibration based on motion trajectory constraint is proposed to solve this problem. This method designs a motion constraint device to control the same motion trajectory of the communicating hose during vibration, establishes a mathematical model based on this, determines the impact of the vibration of the communicating hose on the equivalent sound pressure, and derives an equivalent height calculation formula that is not limited by the open-circuit voltage measurement data of the hydrophone. A hydrostatic excitation method hydrophone calibration device based on motion trajectory constraints is built and compared with traditional methods. Experimental results indicate that, compared to the traditional hydrostatic pressure stimulation method, the proposed method reduced the uncertainty in hydrophone sensitivity calibration from 0.34 dB(k=2) to 0.25 dB(k=2), with the uncertainty introduced by measurement repeatability decreasing from 0.12dB to 0.02dB.
2024 Vol. 45 (11): 1709-1717 [Abstract] ( 41 ) HTML (1 KB)  PDF (564 KB)  ( 4 )
1718 A Combined Measurement and Modeling Approach for Characterization of the Peak Sound Pressure at the Focus of High Intensity Focused Ultrasound Fields
WU Delin,ZHANG Hengda,ZHU Huaiqiu,WU Jian,GAO ShenpingWANG Hongyuan,YU Xingyan,ZHENG Yinfei,YAO Lei
DOI: 10.3969/j.issn.1000-1158.2024.11.17
A method to determine the focal peak sound pressure of the high intensity focused ultrasound field was proposed. Under low amplitude linear propagation conditions, linear pressure waveforms were measured and modeled in water a focused transducer with nominal aperture of 60mm and focal length of 75mm. The corrected parameters input to a Westervelt numerical model were determined based on experimental low amplitude beam plots. The simulated nonlinear waveforms at the focus were obtained, which were distorted strongly with a discrepancy between the peak compressional and rarefactional pressures. The first three harmonics were extracted from the distorted wave by a zero-phase band-pass filter, showing that the relative phases almost keep constant as the source pressure increases. Measurements were performed with a fiber optic probe hydrophone as the focused transducer driving with high-energy. Combined the measured pressure amplitudes with simulated phases of first three harmonics, the peak sound pressure at the focus was obtained. For this focused transducer driving in 250Vp-p, its peak compressional pressure is 7.56MPa, and rarefactional pressure is 4.98MPa.
2024 Vol. 45 (11): 1718-1723 [Abstract] ( 48 ) HTML (1 KB)  PDF (538 KB)  ( 3 )
1724 Comparative Study of Precision Measurement Methods for Antenna Radiation Pattern
LI Huajun,WEI Pin,MENG Donglin,WANG Weilong
DOI: 10.3969/j.issn.1000-1158.2024.11.18
In areas such as microwave remote sensing and deep space exploration, it is expected that accurate antenna radiation patterns can be obtained in order to acquire realistic observations by inverting the visibility function. Therefore, there is an urgent demand of quantitative measurement error from different methods to measure radiation patterns. From the perspective of metrology, quantitative studies by comparing between precision measurements and simulations are conducted. The precise measured data for the standard gain horn antenna show that among far-field method, planar near-field method and spherical near-field method, the conclusions can be drawn : 1) the spherical near-field method has the best zero-depth effect, the far-field method is the worst, and the planar near-field method is in between the two. 2) The effective angular range of the plane near-field method is located within ±60°, beyond this range, the truncation error increases sharply and becomes invalid. 3) the far-field method shows obvious ripple outside the angular range ±80°. Another comparison shows that the spherical near-field method and the compact field method have a better agreement effect, but the curves from the former are smoother. For linear array antennas, the simulated technology is used to study comparatively the accuracy of the three near-field methods. The quantitative research results can be a guide to select the right antenna measurement system and improve the accuracy of radiation pattern measurement.
2024 Vol. 45 (11): 1724-1732 [Abstract] ( 41 ) HTML (1 KB)  PDF (956 KB)  ( 3 )
1733 Research on THz Portable Cold Noise Standard Source
LUAN Peng,LIU Chen,DU Jing,WANG Yibang,HUO Ye,WU Aihua
DOI: 10.3969/j.issn.1000-1158.2024.11.19
The working principle, structural characteristics, performance verification, and uncertainty evaluation of the 170~260GHz portable cold noise standard source newly developed by the 13th Research Institute of China Electronics Technology Group Corporation is introduced. The device adopts a matched wedge load immersed in a rectangular waveguide cooled by liquid nitrogen, and transmits noise power directly to the output waveguide port at room temperature through the waveguide transmission line. By simulating the design and reliable installation of wedge loads, low reflection output of the noise source is achieved. A vacuum pumping scheme is adopted to make the noise source portable, and accurate calibration of the noise source is achieved based on precise temperature control.Through analysis and experiments, it is shown that the output standing wave ratio of the standard source is less than 1.2, the output noise temperature is less than 140K, the uncertainty of output noise temperature is less than 7K (k=2).
2024 Vol. 45 (11): 1733-1737 [Abstract] ( 44 ) HTML (1 KB)  PDF (490 KB)  ( 4 )
1738 Stability and Quenching Correction Accuracy Study of 3H & 14C LiquidScintillation Reference Sources Based on Diisopropylnaphthalene
XIAO Yang,ZHANG Hui,MA Yan,LIU Meiling,LIU Haoran,LIANG Juncheng,ZHANG Jinzhao,ZHAO Qing,FAN Zihao,ZHANG Han,LIU Peng,FAN Fuyou,DAI Xiongxin
DOI: 10.3969/j.issn.1000-1158.2024.11.20
To establish a quenching correction method for 3H and 14C in aqueous samples with commercial liquid scintillation cocktails, unquenched reference sources and quenched series reference sources of 3H and 14C were prepared with DIN (Diisopropylnaphthalene) scintillation cocktails. The stability of the reference sources was investigated in dark condition at room temperature. The change of the correction efficiency of the quenched series of reference sources was less than 0.5 % after 16 months. The slopes of activity and tSIE of the unquenching reference sources of 3H and 14C were lower than the critical value during 30 months, which meant that these reference sources were stable. The quenching correction accuracy of toluene and DIN quenched series reference sources was compared by correcting 3H and 14C samples consisted of different commercial liquid scintillation cocktails. As a result, the correction curve of DIN reference sources was more suitable for commercial liquid scintillation cocktails such as Ultima GoldTM AB, Ultima GoldTM LLT and Optiphase HiSafe 3.
2024 Vol. 45 (11): 1738-1744 [Abstract] ( 71 ) HTML (1 KB)  PDF (516 KB)  ( 4 )
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