计量科学与技术

Improved Nonlinearity Correction Method for Homodyne Orthogonal Signals in Vibration Calibration

HU Hongbo

2024, 68(5): 3-10, 31. doi: 10.12338/j.issn.2096-9015.2024.0064

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Addressing the issue of nonlinearity correction for homodyne interference signals in vibration calibration, this paper describes an improved ellipse fitting algorithm. Compared to the traditional Heydeman ellipse correction method based on least squares, the proposed method makes two improvements. First, it adds constraints on the ellipse parameters in the fitted conic equation. Second, it transforms the conventional parameter calculation based on the minimum distance criterion into solving the eigenvalues of the data matrix. The proposed method ensures that even when the Lissajous figure formed by the homodyne interference signal is only a partial ellipse, a complete ellipse can still be fitted. This extends the working frequency range of the homodyne interferometer in vibration calibration while improving the measurement accuracy.

A Net Power Measurement Method Based on a 3-Port Directional Coupler

LIN Haoyu, HUANG Pan, XIE Jing, LIU Zhipeng

2024, 68(5): 11-16, 76. doi: 10.12338/j.issn.2096-9015.2024.0083

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To address the issue of net power measurement in the field of radio frequency (RF) metrology, a method based on a 3-port directional coupler with mismatch correction is proposed, and the associated uncertainty evaluation is performed. First, the net power calculation equation is rigorously derived using microwave network theory according to the signal flow graph. Second, two experiments are conducted to validate this method. The results show that when using the proposed method to calculate the net power, the typical error is less than 0.1 dB, and it is less affected by impedance mismatch. Furthermore, the experiments demonstrate that the proposed method is suitable for electric field (E-field) probe calibration, as it can reduce the standard E-field strength error caused by the net power measurement. Finally, the uncertainty is evaluated using the Monte Carlo method, and the results indicate that the typical relative standard uncertainty is less than 1.3% when measuring net power using this method. The proposed net power measurement method has the advantages of high accuracy and a simple calculation process, and it has good application prospects in the field of RF metrology, particularly in E-field strength metrology.

Determination and Evaluation of Dosimetric Parameters of Domestic Parallel Plate Ionization Chamber

LI Yihua, LU Gang, WANG Kun, WANG Zhipeng, JIN Sunjun, LIU Yijing

2024, 68(5): 17-23. doi: 10.12338/j.issn.2096-9015.2024.0052

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As a high-sensitivity radiation detector, ionization chambers play an important role in radiotherapy dose calibration and radiation environment monitoring. However, the field of radiotherapy dose measurement is highly dependent on imported equipment, and there is a lack of systematic experimental data supporting the dose stability and reliability of domestic detectors. This study focuses on the domestic QPPC40 parallel plate ionization chamber, quantitatively measuring its key dosimetric parameters in medical accelerator beams. These parameters include energy response, ion recombination, polarity effect, repeatability, leakage current, and dose linearity. The goal is to enhance the dosimetric performance of domestic detectors and provide practical recommendations for clinical applications. The measurement results indicate that the energy response correction factor k_Q for 6 ～ 25 MV photon beam relative to Co-60 γ ray ranges from 0.991 to 0.961, with a repeatability of 0.02%. For 4 ～ 22 MeV electron beams, the k_Q factor ranges from 0.953 to 0.887. At an operating voltage of -400 V, the ion recombination correction values for dose rates of 0.04-5.13 Gy/min range from 1.002 to 1.008. The polarization correction factor is 1.001, and the leakage current is within ±0.05%. The tested indicators generally meet the technical requirements of the JJG 912-2010 verification regulation for therapeutic level ionization chambers. However, the calibration coefficients and energy response consistency of ionization chambers from the same batch show some variability. It is recommended to conduct interim inspections during use and to monitor the long-term stability of the water-absorbed dose calibration coefficient and energy response of the detector.

Analysis and Extension of Validation Methods for SAR Measurement Systems

PANG Xinhua, ZHOU Xin, WU Tong, SHEN Qingfei, TANG Wei, LI Anxiang, MU Xiaotong, YANG Chao

2024, 68(5): 24-31. doi: 10.12338/j.issn.2096-9015.2023.0357

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Specific Absorption Rate (SAR) is a mandatory parameter for the personal safety of electromagnetic radiation involving wireless communication products. Due to the changing nature of the devices under test, the measurement system and methods need to be updated, which imposes new requirements for the validation of the measurement system. Based on an in-depth understanding of the validation methods in current standards, we analyze and measure the traditional validation methods for three steps: extrapolation routine verification, probe linearity verification, and modulation response verification. Using electromagnetic simulations and experimental measurements, we extended these validation methods to meet new testing requirements. The experimental results show that the extended validation methods are feasible and stable. As reference values were obtained through self-developed methods, the validation methods can be extended, allowing for customized validation configurations, such as validation points. This provides technical support for the research on validation methods for new and domestic SAR measurement systems.

Research on Calibration Methods for Anesthetic Depth Monitoring Devices

XIE Taorui, MA Xueran, CHEN Da, LIANG Junhui, DING Xiang

2024, 68(5): 32-36. doi: 10.12338/j.issn.2096-9015.2024.0016

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To address the lack of calibration and performance evaluation methods for anesthetic depth monitoring devices, a new approach is proposed that utilizes real clinical electroencephalogram (EEG) signals to assess the measurement results of anesthetic depth indices. Using a custom-built anesthetic depth monitoring device testing system, EEG signals from young and elderly patients under anesthesia were input into three anesthetic depth monitoring devices, namely BIS index, CSI index, and Ai index. The consistency and repeatability of the measurement results were calculated and evaluated, and the correlation between the indices and the EEG signal spectrum was analyzed. The three indices showed good overall consistency in reflecting the changes in anesthetic state, but significant differences were observed during the anesthetic transition state and in samples from elderly patients. The results indicate that this method can be used for testing the three anesthetic depth monitoring devices and provides guidance for conducting metrological quality control of these devices.

Study on Scale Frequency Measurement and Temperature Influence of Total Station

LIU Yang, LI Lianfu, WANG Deli, JIANG Yuanlin, LI Jianshuang, LIU Xiaodong, MIAO Dongjing, HE Mingzhao

2024, 68(5): 37-43. doi: 10.12338/j.issn.2096-9015.2024.0056

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The total station is a high-precision measuring instrument that integrates distance measurement, angle measurement, and coordinate measurement, playing a crucial role in infrastructure construction and geodetic surveying. Among its various parameters, changes in measuring scale frequency are the main source of distance measurement scale error. This parameter is fundamental to understanding the distance measurement characteristics of the instrument and can essentially characterize the scale error. This paper reports on the development of an automatic measurement system for the total station scale frequency, utilizing high-precision frequency measurement technology referenced to an atomic clock for real-time dynamic measurement. Furthermore, using the developed automatic measurement system, an in-depth study was conducted on the temperature characteristics affecting the scale frequency by controlling the ambient temperature. This research is significant for further evaluating the distance measurement performance of total stations and for identifying the sources of distance multiplication constant errors during calibration and verification processes.

Overview of the Interaction Between the Chemical Composition and Main Physicochemical Properties of Diesel Fuel

DING Chaomin, ZHANG Zhengdong, DU Biao, WANG Guixuan, LIU Fan, LI Qi, LI Ke

2024, 68(5): 44-50. doi: 10.12338/j.issn.2096-9015.2023.0259

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In order to reduce the environmental pollution caused by the use of diesel fuel and to promote the development of the automotive industry towards greater environmental protection and efficiency, China has upgraded diesel quality from China IV to China VI, with increasingly stringent standards for the physicochemical properties of diesel. The quality upgrade has a direct impact on the physicochemical properties of diesel fuel, which are determined by its chemical composition. Therefore, investigating the relationship between the chemical composition and physicochemical properties of diesel fuel can help fuel producers optimize diesel formulations to meet higher quality requirements and assist users in selecting diesel products based on their needs to improve diesel utilization and reduce environmental pollution. This study reviews the intrinsic relationships between the chemical composition of diesel fuel and its density, cetane number, lubricity, low-temperature fluidity, sulfur-containing compounds, nitrogen-containing compounds, and fatty acid methyl esters (FAME). This study provides a theoretical basis for diesel blending and quality upgrading, as well as a useful reference for sustainable energy development and environmental protection.

Calibration of the Field of View Directional Response Function of Infrared Spectroradiometers

MEN Yutong, ZHANG Xinda, AN Baolin, HUAN Kewei, DONG Wei

2024, 68(5): 51-56, 64. doi: 10.12338/j.issn.2096-9015.2023.0330

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In the field of infrared radiation characteristics measurement, Fourier transform infrared (FTIR) spectroradiometers are commonly used measurement units. The field of view (FOV) directional response function is one of the main sources of uncertainty, which manifests as varying responsivity at different locations when the measurement target deviates from the center of the FOV. Currently, most studies on FOV directional response employ medium-temperature, conventional-sized blackbodies as radiation sources, resulting in limited spatial resolution. In this study, a high-temperature, small-sized blackbody radiation source is used to investigate the FOV uniformity of FTIR spectroradiometers, and the directional response function under a typical FOV of 75 mrad is obtained. The variation of spectral responsivity in the uniform region of the FOV is analyzed, and a correction function for the FOV directional response characteristics is proposed and experimentally verified. The results show that after applying the proposed correction function, the responsivity uniformity in the uniform FOV region increases from 92% to 98%.

Development of a Vacuum Blackbody Radiation Source with Large Aperture and Wide Temperature Range

ZHOU Jingjing, HAO Xiaopeng, SONG Jian, GUO Guorui, LIU Zhiyi, XU Chunyuan

2024, 68(5): 57-64. doi: 10.12338/j.issn.2096-9015.2024.0044

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Vacuum blackbody radiation sources are crucial instruments for the radiometric calibration of infrared remote sensing payloads in ground laboratories. To meet the trend of infrared remote sensing payloads towards larger apertures, wider temperature ranges, and higher quantification, a vacuum blackbody radiation source with a 300 mm aperture, a temperature range of 160–380 K, and an emissivity of 0.9975 was developed. This paper introduces the working principle and structural design of the large aperture and wide temperature range vacuum blackbody radiation source. It includes the calculation of emissivity and thermal simulation of the blackbody. The uniformity and stability of the bottom temperature of the blackbody within the 160–380 K range under vacuum low-temperature conditions were tested. The results show that the bottom temperature uniformity is better than 0.120 K and the temperature control stability is better than 0.031 K/30 min. The blackbody cavity emissivity was measured using a method based on controlling environmental radiation, and the spectral radiance temperature was measured using a vacuum low-background infrared radiance temperature standard device. The combined standard uncertainties of the radiance temperature at 10 μm were 0.044 K@160 K, 0.099 K@280 K, 0.095 K@380 K, 0.122 K@380 K. The developed vacuum blackbody radiation source with a large aperture and wide temperature range can meet the radiometric calibration requirements of infrared remote sensing payloads in ground laboratories, supporting the enhancement of China's quantitative level of infrared remote sensing.

Development of Calibration Equipment for PM_2.5/PM₁₀ Separators with Variable Flow Rates

XU Xiao, CHI Shunxin

2024, 68(5): 65-69. doi: 10.12338/j.issn.2096-9015.2024.0040

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The widespread use of low-flow-rate separators in particulate matter monitoring has highlighted a need for traceable calibration. This study focuses on developing calibration equipment for variable flow rate separators. By designing various aerosol atomizing nozzles and incorporating cyclone mixing and isokinetic sampling techniques, the calibration equipment was developed for PM_2.5/PM₁₀ separators operating at flow rates ranging from 1 to 16.7 L/min. The equipment addresses several technical challenges associated with flow rate variations during calibration. The deviation between the actual and working flow rates is within ±1%, and the expanded uncertainty of the D_a50 calibration results is better than 3% (k=2), meeting both domestic and international standards.

Establishment of Standard Reference Dataset for Hazardous VOCs in Ambient Air

BAI Lu, LIU Zilong, LUO Yuqi, XIONG Xingchuang

2024, 68(5): 70-76. doi: 10.12338/j.issn.2096-9015.2024.0061

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Currently, countries around the world are increasingly focused on managing harmful volatile organic compounds (VOCs) in ambient air. Data on harmful VOCs are becoming crucial for atmospheric environmental monitoring and control, significantly increasing in importance. The lists and information on harmful VOCs in the standards, regulations, and policy documents issued by various countries are scattered, and there is no centralized search channel or document that fully covers the VOCs data published by different countries. This makes it difficult to comprehensively and effectively utilize harmful VOCs data and information. Based on the chemical characteristics of harmful VOCs compounds, atmospheric environment monitoring and control, and the requirements for digital calibration certification and recognition of standard reference data, this article designs a technical route for establishing a dataset of harmful VOCs compounds and its establishment methods. The establishment process is completed in practice. The harmful VOCs reference dataset has become a standard dataset after self-assessment, data inspection, comparison between Chinese and American datasets, and expert review. This dataset is publicly available on the official website of the National Metrology Science Data Center, providing important data resources such as authoritative maps of harmful VOCs for scientific research and the development of the environmental protection industry. It greatly enhances scientific research autonomy and has reference value for the governance and research of harmful VOCs. It also lays the foundation for subsequent digital calibration certification and recognition.

Research and Establishment of a New Impedance Traceability System Based on the New Calculable Capacitor Primary Standard

YANG Yan, HUANG Lu, WANG Wei, DAI Dongxue, CHEN Yan, LU Wenjun, LU Zuliang

2024, 68(5): 77-82, 109. doi: 10.12338/j.issn.2096-9015.2024.0070

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Supported by the National Science and Technology Support Program and the National Key R&D Program, the National Institute of Metrology, China (NIM), has undertaken research and established a new AC impedance traceability system based on the new generation calculable capacitor. This includes the creation of new primary standards for capacitance and inductance, as well as AC resistance standards. The new systems have enabled the precise realization of the capacitance unit "Farad" and the inductance unit "Henry", enhancing the traceability capabilities for dissipation factor standard, capacitance working standard, inductance working standard, and AC resistance standard. This work has also included revising the calibration systems for capacitance, inductance, and dissipation factor measuring instruments, as well as updating regulations and specifications for standard capacitors, standard inductors, AC resistors, capacitor boxes, inductance boxes, and AC resistance boxes. As a result, a new AC impedance traceability system for China, based on the new generation calculable capacitor, has been established.

Research Progress on Narrow Linewidth Lasers Based on Whispering Gallery Mode Microcavity

XIN Yunfei, WANG Jin, ZHANG Cheng, LI Daifu, YE Zihan, PAN Yijie

2024, 68(5): 83-91. doi: 10.12338/j.issn.2096-9015.2024.0092

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Narrow linewidth lasers play a vital role in cutting-edge fields such as quantum technology, time-frequency transmission, and high-precision sensing due to their extremely low phase noise. Whispering gallery mode optical microcavities, owing to their high quality factor, tiny mode volume, and wide optical transparent window, can significantly enhance the interaction between light and matter. These microcavities not only achieve good laser linewidth narrowing effects across a wide spectral range but also offer excellent tunability, making them a hot topic in narrow linewidth laser research. This paper reviews the research progress of narrow linewidth lasers based on whispering gallery mode microcavities. It first introduces whispering gallery mode microcavities, their thermal noise theoretical foundation, and the principles of laser linewidth evaluation. Then, it discusses the main methods for generating narrow linewidth lasers using whispering gallery mode microcavities, including pumped narrow linewidth lasers based on stimulated Brillouin scattering and stimulated Raman scattering effects, as well as locked narrow linewidth lasers using self-injection locking and Pound-Drever-Hall (PDH) locking technologies. The research status, key technical characteristics, and performance metrics of these methods are summarized. Additionally, the research progress of the National Institute of Metrology in developing narrow linewidth lasers based on high quality factor crystal whispering gallery mode microcavities is introduced. Finally, the paper provides a summary and outlook on the development of narrow linewidth lasers based on whispering gallery mode microcavities.

Research on Photovoltaic Metrology at the National Institute of Metrology, China: A Review

MENG Haifeng, ZHANG Junchao, LIU Wende, XU Nan, WANG Meng, ZHANG Bifeng, CAI Chuan, MAN Shuai, DENG Wenhao, XIONG Limin, GAN Haiyong

2024, 68(5): 92-99, 126. doi: 10.12338/j.issn.2096-9015.2024.0062

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Photovoltaic (PV) power generation is one of the most promising renewable and clean energy technologies, and China has become the world's largest producer, user, and exporter of photovoltaic products. Accurate and reliable measurement of the photoelectric performance parameters of PV products is critical for their scientific research and industrial development. Based on the traceability and dissemination system established by the National Institute of Metrology, China (NIM), China's photovoltaic industry has achieved effective traceability and dissemination of key quantities. This article reviews the research and establishment of the traceability and dissemination chain for China's photovoltaic industry, from the highest relevant standard, the cryogenic radiometer, to terminal PV products, and provides prospects for the next stage of research.

Research Progress in Accurate Mass Spectrometry-Based Measurement Methods for Lipid Fine Structure

CHENG Simin, TAN Siyuan, YIN Xinchi, GONG Xiaoyun

2024, 68(5): 100-109. doi: 10.12338/j.issn.2096-9015.2024.0010

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Lipids are essential functional biomolecules within cells, characterized by their abundant quantities, diverse species, and versatile structures. In recent years, numerous scholars have devoted efforts to developing advanced techniques for the accurate characterization of lipid fine structures, aiming to identify novel lipid molecules as disease biomarkers and for lipid functional research. Lipid reference materials play important roles in the qualitative and quantitative analysis of lipids, but due to the diversity of lipid fine structures, their preparation and quantification are challenging tasks. Mass spectrometry (MS), renowned for its robust capability in accurate compound structure measurement, has gained significant attention in the field of lipid fine structure characterization. MS-based analytical methods for lipid fine structure analysis have rapidly progressed, offering a novel perspective for lipid study, deepening our understanding of lipid structural diversity and the lipid metabolic network. Moreover, these methods have propelled the screening of potential disease biomarkers and the discovery of new metabolic pathways. Currently, MS-based analytical methods for accurate lipid fine structure measurement primarily employ two strategies: novel ion activation/dissociation methods and specific chemical derivatization. These approaches demonstrate excellent analytical performance for a variety of lipid fine structure isomers. This review summarizes the MS-based analytical methods for lipid fine structure and provides an outlook on their applications in the preparation of lipid reference materials.

Research on the Funding Effectiveness of National Major Scientific Research Instrument Development Projects Based on Bibliometrics

LI Xiaomeng, SHANG Xueshen, FAN Wen, SUI Zhiwei, LI Dabo, WU Aihua, LIU Yulan, LIU Yitong

2024, 68(5): 110-120. doi: 10.12338/j.issn.2096-9015.2023.0274

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Scientific research instruments are the foundation and achievements of scientific and technological innovation. In the context of a new round of scientific and technological revolution and industrial transformation, they have become the focus of global competition in scientific and technological innovation, including in China. Taking the scientific research output of the National Major Scientific Research Instrument Development Projects (NMSRIDP) as the research object, this study employs bibliometric analysis to reveal the quantity, quality characteristics, and internal patterns of scientific papers from various dimensions, such as output quantity, published journals, citation frequency, and output institutions. Additionally, by analyzing highly cited papers and hot papers, this study evaluates the funding effectiveness of the NMSRIDP from 2011 to 2022 in terms of output, impact, input-output ratio, and other aspects. The aim is to provide a basis for the performance evaluation of the output and achievements of science fund projects and to offer valuable insights into the crucial role of the instrument fund in promoting breakthroughs in China's frontier basic research.

Practice and Discussion on the Management of Science and Technology Awards in Research Institutions: A Case Study of National Institute of Metrology, China

RONG Jie, YANG Fan, YU Xiahui, YANG Dong, CHEN Jun, LU Zhuhua

2024, 68(5): 121-126. doi: 10.12338/j.issn.2096-9015.2024.0022

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Science and technology (S&T) awards are an important measure to stimulate the vitality of scientific and technological innovation among researchers. As the highest national research center for metrology in China, the National Institute of Metrology, China (NIM) has long placed great emphasis on encouraging scientific and technological innovation. By establishing the NIM Science and Technology Award, NIM further stimulates researchers' enthusiasm for innovation, promotes the development of scientific and technological innovation, and creates a favorable research and innovation ecosystem. Based on historical data, this paper systematically reviews the application and awarding of the NIM Science and Technology Award from 2006 to 2022. In response to the phenomenon of a continuous decline in the number of award applications discovered during the management process of S&T awards, the paper analyzes the existing problems and their causes. It summarizes the experience, practices, and management effectiveness of stimulating researchers' enthusiasm for applying for awards by adding a youth S&T award, adjusting award levels, and increasing award incentives. Suggestions are put forward to further optimize the award management system, increase the publicity of achievements and popularization of science, and improve the information system.

2024 Vol. 68, No. 5

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