计量科学与技术

2021, (12): 1-1.

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Application of Standard Impact Specimen in Verification of Instrumented Pendulum Impact Testing Machine

LUO Xin, LI Tianwu, LI Shishuai, HU Bolun

2021, 65(12): 3-6. doi: 10.12338/j.issn.2096-9015.2021.0152

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By analyzing the test results of instrumented pendulum impact test method, the applicability of standardimpact specimen in indirect verification of instrumented pendulum impact test machine(Hereinafter referred to as testing machine) is studied. Comparing the characteristic curve of impact process with the absorbed energy of standard sample, the results show that it is more scientific and reasonable to use Charpy V-notch standard sample for indirect verification of instrumented pendulum impact testing machine.

Study on Mass Acceleration Distribution for Dynamic Force Analysis

YIN Ruiduo, GUO Xiaowei, XIAO Yao, ZU Hongfei, LI Yilong

2021, 65(12): 7-11. doi: 10.12338/j.issn.2096-9015.2021.0161

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Based on the principle of relative sinusoidal force calibration, this paper studied the axial and radial acceleration distribution of aluminum cylindrical mass with radius of 70mm and height of 30mm through theoretical derivation, experimental test and simulation analysis. Firstly, the acceleration distribution law of each position of the mass was deduced and obtained; Secondly, the acceleration distribution of mass was tested at each characteristic point; Finally, the mass was modeled and simulated to obtain the axial and radial acceleration distribution, and the results were compared with the theoretical and simulation results. In the axial direction, the theoretical, simulation and experimental results are in good agreement; In terms of radial, the simulation and experimental results are in good agreement, which can be used to modify the absolute stiffness assumption in the future.

Experiment and Data Analysis of Digital Adjustable Pipette Based on Different Working Modes

LIU Yan, ZOU Rong

2021, 65(12): 12-14, 44. doi: 10.12338/j.issn.2096-9015.2020.0402

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This paper introduces the working principle and three working modes of the digital adjustable pipette, expounds the verification method and steps of the digital adjustable pipette, gives the data analysis method, and analyzes the influencing factors of the accuracy of the measurement results. Through the comparative experiment of capacity error and repeatability of three working modes, including ordinary mode, mucus mode and liquid separation mode, the advantages and disadvantages of the three working modes are verified.

Improving Accuracy of the Measurement System for Railway Tanks

MA Kewen, ZHAO Jing

2021, 65(12): 15-16, 54. doi: 10.12338/j.issn.2096-9015.2020.0004

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To improve the accuracy of the train filling and measuring system is important for maximizing the utility of system, including avoiding over-loading and under-loading, and reducing delay of the filling work, measuring by ruler, and sales and freight transportation. Through an on-site investigation of a loading mass flowmeter and the loading process, the main factors causing errors were analyzed, and practical and effective solutions were put forward. The efficiency of the train tank loading was obviously improved and the manual labor for gauging was greatly reduced.

Understanding and Evaluating the Durability of Weighing Instruments

SHENG Baizhan

2021, 65(12): 17-21, 65. doi: 10.12338/j.issn.2096-9015.2020.0146

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Shared description of "durability" from various standards is summarized. The difference between "durability" and "stability" is analyzed. The essence of wear-out and life regarding durability of non-disposable weighing instruments is pointed out. The test objects, test items, test occasions and test sites for evaluating the durability of weighing instruments are analyzed. Based on the understanding of the durability of weighing instruments, discussions are made on the durability test clauses in existing international recommendations or national standards. Difference between the in-service inspections carried out by legal metrology institutes and by users are examined. The following items are compared for durability tests made on type evaluation, on initial verification and subsequent verification, and on in-service inspection carried out by legal metrology institutes or users: test occasions, test objects, test functions, test purposes, test proposers and executors, test sites and working conditions, the criteria of durability, and the documents in which the test results should be included.

Development of an Infrared Photoelectric Impact Velocity Measuring Instrument

FANG Nanjia, WU Peigang

2021, 65(12): 22-25, 44. doi: 10.12338/j.issn.2096-9015.2021.0531

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In order to calibrate energy loss of drop hammer impact testing machines, a portable speed measuring device using a photoelectric sensor to measure the impact speed was developed. The device is mainly composed of a grooved infrared photoelectric sensor, two fixed distance cylinders, a multifunctional pulse meter and a magnetic meter base. The measurement principle: when the hammer falls at a certain speed, it drives two cylinders with a fixed distance in between to go through the sensor one after the other. A multi-functional pulse meter reads the time interval between the two cylinders covering the sensor, and then the impact speed is calculated based on the distance and time interval between the cylinders. Based on the calibration parameters, a mathematical model was established and the measurement uncertainty was evaluated. For impact speeds not greater than 10 m/s, the maximum error of measurements is within ± 0.25%. The device can be used to measure the speed of transverse impacts, inclined impacts, and vertical impacts of packaging.

The Calibration System and Uncertainty Evaluation for Torque Rating of Bottle Cap Torque-meters

WU Zhiyu, LI Jing, ZHENG Xiaolan, WANG Hui, CHEN Haibin

2021, 65(12): 26-29. doi: 10.12338/j.issn.2096-9015.2021.0086

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A device for meauring torque rating of bottle cap torque-meters was developed. The device includes a special check lever, a force weight loading mechanism, and a horizontal to vertical loading mechanism. The torque rating was measured by multiplying the force value of the weight and the arm length of the check lever. Factors affecting measurement uncertainty were analyzed and the uncertainty in the measurement results of the torque rating was evaluated. The results showed that the performance of the device was stable and reliable. It can be used to calibrate bottle cap torque-meters of level 1 or below and small range special torque testers, providing traceability for their torque indication.

An Enveloping Model of the Minimum Tolerance Zone Method for Evaluating Straightness in a Plane and the Associated Algorithm

GAN Jianghong, ZHANG Xinbao

2021, 65(12): 30-34, 69. doi: 10.12338/j.issn.2096-9015.2020.0361

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According to the geometrical description of straightness error presented in the national standard GB/T 11336-2004, a new enveloping model of the minimum tolerance zone method for evaluating straightness in a plain and a principle for judging envelop points are proposed in this paper. Based on the principle, a highly efficient algorithm is proposed to search for the envelope points. The proposed algorithm is suitable for searching for the envelope points of a mass points set. A comparison with a traditional method shows that the proposed algorithm had good completeness and produced reliable results. By means of simulation, sets of a million points were calculated using the algorithm and the costs of the algorithm were recorded. The result showed that the time complexity of the algorithm was O(N). The enveloping model proposed in this paper is simple and accurate.

An Evaluation System for Natural Gas Flow Computers

PEI Quanbin, QING Qing, CHEN Zhengwen, XUE Yongxin

2021, 65(12): 35-39. doi: 10.12338/j.issn.2096-9015.2020.0246

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Flow computers are an important measuring instrument for natural gas measurement and trade. It is necessary to formulate requirements and a test standard for evaluating the structure, performance, safety, and consistency of flow computers. Test software for natural gas flow computers was developed, having functions of data collection and evaluation, flow calculation and verification, and evaluation of physical parameters and environmental factors. A test syste for evaluating natural gas flow computers and associated sensors was then developed. Tests were carried out on the system in

A Method for Testing Influence of Flow Field Disturbance on Ultrasonic Gas Meters

JIANG Hangcheng, LIN Mingxing, LI Hang, YANG Yang

2021, 65(12): 40-44. doi: 10.12338/j.issn.2096-9015.2021.0138

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According to the analysis of gas velocity in different sections of a pipeline, the velocity is related to the position of the section. Ultrasonic gas meters measure the cumulative volume by measuring the average velocity of the gas. Flow field disturbance affects the gas velocity distribution in the pipeline and the measurement accuracy. A gas meter is disturbed by two types of flow fields, namely velocity distribution distortion and vortex. This paper proposes a test method for two kinds of flow field disturbance, and focuses on the structure, installation and error algorithm of the disturbance generator. Taking the 1.5 grade G6 diaphragm gas meter as an example, a 0.5 stage sonic nozzle method gas flow standard device was used to test the influence of flow field disturbance under the flow rate of 10 m³ / h. The influence was less than 0.1%. Given the fact that diaphragm gas meters are not affected by flow field disturbance, the feasibility of the method and the accuracy of the algorithm were verified, providing an evaluation method for verifying the adaptability of ultrasonic gas meters to flow field disturbance. It can be used to obtain more complete and accurate test data of ultrasonic gas meters in design and optimization of flow channels, leading to better product quality. The test data of the G6 ultrasonic gas meter showed that it was easily affected by flow field disturbance. The change in the error caused by the disturbance on the inlet side at the flow rate of q_max was 0.30%, greater than the change of 0.11% on the outlet side, and the changes were related to the flow rate. This effect was insignificant at the flow rate of 0.2q_max. In the design of a product, the flow field should be optimized to reduce flow field disturbance.

Study on Techniques of Extraction and Testing of Residual Solvent in Carbon Fibers

ZHAO Deming, ZHANG Shun, CONG Jiayue, WANG Dan, WANG Lu, LI Changqing

2021, 65(12): 45-48, 11. doi: 10.12338/j.issn.2096-9015.2021.0101

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Because of their excellent mechanical properties, polyacrylonitrile(PAN)-based carbon fibers are widely used in aerospace, general industry, high-end sports goods, etc. High purification and densification of carbon fiber precursors is one of the key techniques for the preparation of high-performance carbon fibers. During the extraction and testing of the residual solvent in carbon fiber precursors, boiling water causes the decomposition of the residual solvent in the dimethyl sulfoxide (DMSO), which seriously affects the accurate quantification of the residual solvent in the fibers. A systematic study of accurate extraction and quantification of residual solvent dimethyl sulfoxide (DMSO) in carbon fiber precursors was carried out at the National Measurement and Testing Center for Carbon Fiber Industry. Water, ethanol, acetone, and cyclohexane were used as extraction agents. The effects of extraction agent types, fiber quality, extraction temperature and time, and measuring instruments on the accurate quantification were studied. The extraction conditions and quantitative testing methods were proposed to provide measurement and testing services for improved process control of the preparation of high-performance fibers.

Discussions on Calibration and Verification Methods for Measuring Gain Compression of Spectrum Analyzers

LIU Guibin, LIANG Qi, SU Teng

2021, 65(12): 49-54. doi: 10.12338/j.issn.2096-9015.2020.0401

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Gain compression is an item that should be measured specified in the calibration specification and verification regulation for spectrum analyzers. However, the calibration method and the verification method for measuring gain compression are not perfect. The definition of gain compression, common methods of measuring gain compression, and the shortcomings in the calibration method and the verification method are analyzed in this paper. An improved two-tone compression method for measuring gain compression is proposed. It was verified that the new method can measure the 1 dB gain compression point of spectrum analyzers correctly. The method can be used as a supplement to the exiting calibration method and verification method.

A Ball Diameter Measuring Instrument Based on Optical Interferometry for Hemisphere Dynamic Pressure Motors

DUAN Rong, WANG Jing, YUE Chunguo, DONG Qingyu

2021, 65(12): 55-59. doi: 10.12338/j.issn.2096-9015.2021.0032

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As the precision of the spherical couple parts (i.e. the hemisphere and the ball bowl) of a hemisphere dynamic pressure motor is very high, their ball diameter and sphericity measurement during fabricating process have to rely on high precision three-dimensional and roundness measuring instruments. Therefore the measuring process is tedious, complicated, time-consuming, and inefficient. For a long time, it has been one of the bottlenecks that reduce efficiency in the manufacture of hemisphere dynamic pressure motors. In this paper, a ball diameter measuring instrument developed on the basis of the principal of optical interference is introduced. Its application showed that it featured simple operation, high precision, and visible results. It can be used for in-situ measurement while the parts are under fabrication, which greatly improves the measurement efficiency. It has great potential for increasing the efficiency of manufacture of hemisphere dynamic pressure motors and other spherical parts as well.

Determination of Arsenic and Cadmium in Powdered Rice by Inductively Coupled Plasma-Mass Spectrometry and Evaluation of the Uncertainty

ZHANG Zaiping, WANG Yu

2021, 65(12): 60-65. doi: 10.12338/j.issn.2096-9015.2019.0427

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The microwave digest technique combined with inductively coupled plasma-mass spectrometry (ICP-MS) was used for the determination of arsenic and cadmium in powdered rice. The measurement uncertainty was evaluated by establishing a mathematical model. The measurement results of arsenic and cadmium in powdered rice were (0.182±0.012) mg/kg and (0.262±0.016) mg/kg, respectively, with the coverage probability of 95%. The major uncertainty components were from standard curve fitting and test solution measurement. The research method can be used for measurement of harmful elements in powdered rice by ICP-MS.

A Measurement Comparison of Water Turbidity

HUANG Jinmei, GAO Xuhui, CHANG Mei, LI Yu, YU Deshui

2021, 65(12): 66-69. doi: 10.12338/j.issn.2096-9015.2019.0455

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A measurement comparision of water turbidity was carried out among Shanxi Province's legal measurement institutes. Some problems with the participating laboratories found in the comparison are discussed in this paper. Through analysis of the problems, reasonable solutions are proposed, which can improve measurement of turbidimeters.

2021 Vol. 65, No. 12

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