计量科学与技术

Research Progress in Optical Quantum Pressure Standards

MA Kun, YANG Yuanchao, FENG Xiaojuan

2024, 68(10): 3-10. doi: 10.12338/j.issn.2096-9015.2024.0113

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Abstract:
Optical quantum pressure standards offer significant advantages in primary measurement, including extremely high resolution, inherent accuracy, and independence from physical artifacts. These characteristics make them the preferred direction for developing next-generation pressure measurement benchmarks. Numerous metrology research institutions and universities worldwide have conducted relevant studies in this field. This paper introduces the working principle of optical quantum pressure measurement based on Fabry-Pérot cavities. It provides a comprehensive review of the current research status in optical quantum pressure standards both domestically and internationally. The article also recounts the work conducted by the National Institute of Metrology of China to enhance the performance of optical quantum pressure standard devices. This includes research progress in suppressing vacuum outgassing effects, eliminating zero-point errors, and independently determining correction factors. Furthermore, the paper discusses future research priorities and development trends for optical quantum pressure standards.

Application of the Residual Period Method in Low-Frequency Hydrophone Sensitivity Calibration

QU Minglong, DUAN Chao, CAI Yue, ZHANG Kai, XIE Jianyu, ZHAO Peng, GUO Shixu

2024, 68(10): 11-18. doi: 10.12338/j.issn.2096-9015.2023.0279

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This study addresses the challenges in calibrating hydrophone sensitivity at low frequencies, which arise from limitations in water tank dimensions, unavoidable reflections in water pools, and superposition of reflections in the low-frequency range. Building upon the free-field comparison method, we propose a technique that fits the amplitude, frequency, and phase of residual periodic signals to lower the frequency limit for sensitivity calibration. Experimental results demonstrate that this method enables sensitivity calibration in the 2.5-20 kHz frequency range, with errors within 0.6 dB. It effectively eliminates calibration errors caused by reflected sound fields, validating its efficacy in low-frequency calibration. However, the residual period method has some practical limitations. Factors such as environmental noise, attenuation of reflected sound fields, and nonlinear effects can impact the method's accuracy. Despite these challenges, the proposed approach shows promise in expanding the frequency domain for hydrophone calibration, particularly in low-frequency ranges where traditional methods face significant obstacles.

Research on Characterization Methods and Uncertainty Evaluation for Freezing Point Reference Materials

LIU Zhe, HONG Tao, ZHANG Yu, LI Qingwu, ZHANG Zhengdong

2024, 68(10): 19-24, 65. doi: 10.12338/j.issn.2096-9015.2024.0168

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Jet fuel, commonly known as aviation kerosene in China, is primarily represented by No. 3 jet fuel. The freezing point is a crucial indicator of jet fuel's low-temperature fluidity. During flight, as jet fuel temperature decreases, solid hydrocarbon crystallization can occur, potentially blocking filters and compromising flight safety. According to GB 6537-2018, the freezing point of No. 3 jet fuel must not exceed −47°C. Two methods are specified for determining the freezing point: GB/T 2430-2008 "Standard Test Method for Freezing Point of Aviation Fuels" and SH/T 0770-2005 "Standard Test Method for Freezing Point of Aviation Fuels (Automatic Phase Transition Method)," with GB/T 2430-2008 designated as the arbitration method. This study investigates the effects of various factors, including sample volume, cooling bath temperature, and stirring rate, on freezing point measurement results. It also examines the consistency between the two methods and evaluates the uncertainties introduced by the characterization method. Results indicate that a 0.01 mL change in sample volume leads to a 0.07°C variation in test results. Stirring rates between 1 and 1.5 revolutions per second cause a 0.2°C change in measurements. Cooling bath temperatures ranging from −60°C to −80°C have minimal impact on freezing point results. Experimental validation shows a maximum deviation of 0.7°C between the two methods, surpassing the reproducibility requirements of the standard method. The uncertainty components introduced by sample volume, stirring rate, method selection, and data rounding are 0.040°C, 0.058°C, 0.20°C, and 0.14°C, respectively. The expanded uncertainty of the characterization method is 0.50°C (k=2).

Research on Traceability Techniques for Helicobacter pylori ¹³C Breath Test

HAO Jingkun, LIU Yiling, HU Shuguo, MA Xing, XIE Conghui, YIN Dongmei, WANG Defa

2024, 68(10): 25-32. doi: 10.12338/j.issn.2096-9015.2024.0144

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Addressing the challenge of ineffective traceability in Helicobacter pylori ¹³C urea breath test (13C-UBT) in China, this study employed a dynamic continuous generation system to produce reference gases with delta over baseline (DOB) values ranging from 0 to 50‰. The metrological performance of ¹³C breath test equipment was evaluated using these reference gases. Experimental results demonstrated good agreement between the DOB reference gas values and the measurements of the ¹³C breath test equipment, with indication errors at each concentration point less than ±1.5‰ and repeatability within 0.3‰. To simulate human breath conditions (34°C, 90% RH), reference gases were humidified using a standard gas humidification device. The study compared the performance of ¹³C breath test equipment using reference gases under three conditions: simulated human breath (34°C, humidified), room temperature with humidity, and room temperature without humidification (dry gas). Results showed no significant differences or trends among these conditions, supported by theoretical derivations and principle analyses. This demonstrates that altering the temperature and humidity of reference gases does not affect the reported DOB values. Consequently, room temperature dry gas can be used as a reference gas for calibrating ¹³C-UBT analyzers and similar devices, simplifying the traceability process without compromising accuracy.

Investigation of Seismometer Calibration and Consistency with Transfer Function

KONG Chuijie, ZUO Aibin, ZHOU Jinfeng

2024, 68(10): 33-37. doi: 10.12338/j.issn.2096-9015.2024.0055

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This study employs the national standard ultra-low frequency vibration apparatus to conduct sensitivity calibration of seismometers, using the 3T-120PH as a typical example. The vibration calibration data are compared and analyzed against the seismometer's transfer function results. At lower frequencies (below 10 Hz), the vibration calibration results show excellent agreement with the transfer function results. However, at higher frequencies (above 10 Hz), discrepancies begin to emerge between the two methods. The vibration calibration method realistically transmits vibration signals to the seismometer, closely mimicking actual usage conditions. Consequently, the shaker calibration method provides a more accurate representation of the seismometer's performance under real working conditions compared to the electrical calibration method. This study highlights the importance of using appropriate calibration techniques for ensuring the accuracy and reliability of seismometer measurements across different frequency ranges.

Application of CNN-LSTM Model Integrating Prophet and PCA Techniques for Water Quality Prediction

XIAO Ke, ZHANG Jianjun, TAN Wenwu, WANG Li, SONG Lingyu, LIN Haijun

2024, 68(10): 38-44. doi: 10.12338/j.issn.2096-9015.2024.0109

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To mitigate potential error rates in traditional CNN-LSTM models for water quality prediction, this study proposes an enhanced CNN-LSTM water quality prediction method incorporating the Prophet model and Principal Component Analysis (PCA). In the data preprocessing phase, the Prophet model is employed for outlier detection and handling of water quality monitoring data. PCA is then utilized to reduce the dimensionality of influencing variables and eliminate variable correlations. The processed results serve as input for the CNN-LSTM model to predict the total nitrogen index of water quality. Experimental validation of the proposed method demonstrates significant improvements over the standard CNN-LSTM model across three evaluation metrics: Mean Absolute Error (MAE), Root Mean Square Error (RMSE), and Mean Squared Error (MSE). Specifically, the proposed method achieved a 13% reduction in MSE, a 6.7% decrease in RMSE, and a 5.6% improvement in MAE. These results highlight the effectiveness of integrating Prophet and PCA techniques with CNN-LSTM for enhancing water quality prediction accuracy and reliability.

Research on Ultra-High-Speed Signal Acquisition and Signal Integrity Processing Technology

WANG Zhiyu, ZHANG Yue, ZHOU Keji, YANG Guanghong, XIAO Kaige

2024, 68(10): 45-50. doi: 10.12338/j.issn.2096-9015.2024.0130

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As electronic systems evolve towards greater bandwidth, higher transmission rates, and enhanced computing power, the demand for platforms with ultra-high-speed signal acquisition capabilities has become increasingly urgent. Concurrently, technologies for comprehensive signal integrity processing, monitoring, feedback evaluation, and optimization have emerged to complement these platforms. The synergistic development of these capabilities drives effective improvements in high-speed processing technologies, promoting rapid advancements in ultra-high-speed sampling, storage, transmission, and signal integrity-related applications across China's industry chain. This study focuses on ultra-high-speed signal acquisition and signal integrity processing technology based on a self-developed 80 GSa/s (Giga-Samples per second) Analog-to-Digital Converter (ADC) chip. Extensive software-based data processing significantly enhances measurement precision, processing accuracy, and computational efficiency, enabling high-speed signal transmission and processing at an 80 GSa/s sampling rate. For signal integrity processing, conditioning circuits serve as key components, while traceability algorithms form the core of the system. The displayed values are the results of algorithmic calculations, ensuring data accuracy and reliability.

Research and Design of a New RF Voltmeter Calibrator

LIU Yiyang, LI Yong, CHEN Shuo, JIA Chao, CUI Xiaohai

2024, 68(10): 51-57. doi: 10.12338/j.issn.2096-9015.2024.0089

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RF voltage measurement plays a crucial role in scientific research and industry. RF voltmeter calibrators are widely used in metrology stations at all levels of the national metrology system, undertaking numerous calibration tasks. This paper introduces a newly developed intelligent RF voltmeter calibrator that offers several advantages, including wide frequency bandwidth, high dynamic range, high accuracy, and automatic testing capabilities. It provides functions for basic error calibration and frequency additive error calibration, enabling automatic or semi-automatic calibration of various types of RF voltmeters and automatic generation of calibration certificates. The calibrator's design focuses on two aspects: hardware and software. In the hardware design, a standard AC voltage source is developed for basic error calibration. This circuit consists of an AC voltage generator module, a voltage amplification module, and a closed-loop feedback module, ensuring high-accuracy output. For frequency additive error calibration, a new sensor chip and structure are designed to facilitate more accurate and convenient DC voltage calibration. The software design encompasses the measurement and control module, data processing module, and display module. These modules enable automatic value reading for feedback adjustment, switching of ranges or frequencies, value display, and subsequent data processing. The introduced RF voltmeter calibrator design is at the forefront domestically, contributing to the innovation of domestic calibrators, reducing dependence on foreign instruments, and meeting the needs of domestic RF voltmeter verification and calibration.

Research on Automated Detection Methods and Device for Geometric Parameters of Quartz Pendulous Reeds

WANG Jing, CHEN Xiaolei, DONG Qingyu, ZHANG Guorui, CUI Can

2024, 68(10): 58-65. doi: 10.12338/j.issn.2096-9015.2024.0034

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The quartz flexible accelerometer is a fundamental measuring element in inertial navigation systems, used to measure the system's linear acceleration. Due to its advantages of high precision, high sensitivity, and high stability, quartz flexible accelerometers are widely used in the aerospace field. The quartz pendulous reed is the core component of the quartz flexible accelerometer. It senses physical information such as the speed and acceleration of the measured object. The processing accuracy of the quartz pendulous reed affects the performance of the quartz flexible accelerometer. Therefore, it is particularly important to measure the geometric parameters of the quartz pendulous reed. In this paper, an automated measuring instrument for the geometric parameters of the quartz pendulous reed is introduced. Using this system, methods for measuring the thickness, step height, and droop of the quartz pendulous reed based on a chromatic confocal sensor are proposed. The uncertainties of different measurement methods are analyzed. Experimental measurements of the geometric parameters of quartz pendulous reeds demonstrate that the device has the advantages of simple operation and high accuracy. The device achieves automatic detection of the geometric parameters of quartz pendulous reeds, greatly improving detection efficiency and having significant implications for their automated inspection.

Investigation of the Diffraction Efficiency of LiF220 Crystals

WANG Zhen, GUO Siming, HUANG Shikui, LI Zhiwei, ZHOU Xing, SHU Ziyao, FAN Lipeng, WANG Zhongtao

2024, 68(10): 66-72. doi: 10.12338/j.issn.2096-9015.2023.0322

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Using K fluorescence X-rays, we conducted diffraction efficiency experiments on LiF220 crystals at energies of 23.3 keV and 31 keV. By adjusting the Bragg angle of the incident monochromatic X-rays, we measured the diffracted monochromatic X-rays. The experimental results showed that the crystals produced relatively complete diffraction peaks at both energies. Under irradiation at energies of 23.3 keV and 31 keV, maximum diffraction efficiencies of approximately 2.46% and 1.33% were obtained at incident angles of 10.8° and 8.1°, respectively, which are consistent with theoretical values. This study provides experimental data support and reference for research in materials science and other related fields. Measurements of diffraction efficiency can be used to verify the accuracy of experimental results, providing a tool to test experimental conditions and data interpretation, ensuring the reproducibility and reliability of the study.

Application of Infrared Thermography in Measuring the Focal Plane of a Focused Ultrasound Transducer

ZHAO Wei, CAO Huiyuan, WU Yanqi, TAO Jie, YU Yaping

2024, 68(10): 73-78, 72. doi: 10.12338/j.issn.2096-9015.2023.0280

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To better study the acoustic field characteristics of focused ultrasound transducers, this paper proposes a method for measuring the focal region size using infrared thermal imaging technology. By placing a thin-film sound-absorbing material on the focal plane of the transducer and measuring the temperature distribution under ultrasonic power using an infrared thermal imager, the focal size is determined. Additionally, the hydrophone scanning method was used to measure the same focused transducer, and a theoretical analysis of the sound field distribution was conducted. The results showed that the discrepancy in the -6 dB beam width was within 5%, verifying the feasibility of using infrared thermal imaging to measure the sound field distribution of focused ultrasound transducers.

Current Issue
2024 Vol. 68, No. 10

DynamicMORE+

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Current Issue 2024 Vol. 68, No. 10

DynamicMORE+

ScienceMORE+

Current Issue
2024 Vol. 68, No. 10