Abstract: The standards for measurement of petroleum and liquid petroleum products issued by the government are used to guide and standardize measurement of oil products. Using an example of great errors in measurements of crude oil tanker caused by non-standard operations, this paper analyzes the causes of the errors, so as to make the measurement standards better adopted in practical operations and reduce measurement errors.
Abstract: To complete the inspection of the X-axis positioning accuracy of the inclined-bed CNC lathe more smoothly, we introduce several laser interferometer optical path adjustment methods by summarizing a lot of working experience and clarify the principle and steps of using laser interferometer optical path adjustment methods. The method makes good use of the characteristics of the adjustment accessories equipped with the interferometer and solves the difficult problem of adjusting the optical path collimation of the inclined axis.
Abstract: Ultra low temperature refrigerators are widely used in biological research, clinical medicine, etc. The accuracy of the temperature in a refrigerator directly affects the quality of the samples stored in the refrigerator. Regular calibration of refrigerators is needed to ensure the reliability of their performance. Considering actual situation of on-site calibration, this paper discusses the common problems in calibration of ultra-low temperature refrigerators, such as the selection of calibration instruments, calibration methods, safety protection measures, and gives relevant suggestions.
Abstract: The measurement performance of ultrasonic gas meters is, theoretically, independent of the object (i.e. the medium) they measure. However, due to the different acoustic impedances of gas and air, the transmittance of sound waves in the two media is different; due to the difference in shear viscosity and molar mass, the attenuation of sound waves is different. A standard piston-type flow device, with a flow range of (0.016～10) m3/h, the maximum working pressure of 10 kPa and expanded uncertainty of Urel=0.33% (k=2), was used to test three 1.5-level G4 ultrasonic gas meters. The test data showed that 1# had zero drift, which caused its large and medium flow point error to be −5.61% compared to air, and 3# had a wrong-wave and zero-drift phenomenon, which caused its small flow point to have an error of −15.22% compared to air. Therefore, it is recommended that the relationship between gas and air be a mandatory item in type evaluation.
Abstract: The rapid development of science and technology imposes increasingly demanding requirements for casting in the casting industry. Automatic casting techniques are key to high quality and productivity of high-speed molding production lines. Breakthrough in production techniques is the main research direction in intelligent casting. In order to meet the needs of applied technology, based on existing casting machines, a mass flow weighing system for casting machines for measurement in trade was developed. The system is easy to control and has a relatively compact structure.
Abstract: Based on the 20L bell jar gas flow standard device in our station, this paper briefly introduces its technical parameters, basic structure and working process. The static volumetric method was used to verify its performance. The verification process is introduced in detail and the verification requirements with the static volumetric method are explained in detail through examples.
Abstract: Dynamic truck scales are key equipment for non-parking weighing at the entrance of expressway toll stations and checking the weight of trucks at the exit of expressway toll stations. Hence they play a vital role in protecting highway traffic. The error in weighing results has a direct influence on interests of truck drivers.The eccentric loading test is always overlooked in daily verification of dynamic truck scales due to the fact that it is time-consuming. In this paper, the role of the eccentric loading test in verification is analyzed and the significance of the eccentric loading test is determined by comparing and analyzing the influence of different eccentric loading values on weighing results of dynamic truck scales, with a view to shed light on the application of eccentric loading tests in daily verification of dynamic truck scales.
Abstract: In view of the current situation of liquid level measurement for the separator in an unattended gas gathering station, this paper analyzes problems existing in the current liquid level measurement and puts forward a new measurement method similar to double eye observation.
Abstract: In measurement of environmental particles, PM2.5 separators are a core component for screening of particle sizes and accurate collection of particles. The test and evaluation of separation performance is of great significance in research on particle meters. The separation performance test device is used to evaluate the separator’s performance, which can give the performance curve and judge whether the separator meets the designed requirements. So the test device affects the accuracy of the separation performance. Through the evaluation of the key parameters, feasibility and comprehensive performance of the test device, it will provide a theoretical and experimental basis for the accuracy and reliability of the device in application.
Abstract: In order to solve the problems of misalignment, failure and even damage of clamp ammeters in operation due to that the new energy power generation, grid connection and nonlinear load bring DC components to the AC power supply system, the disadvantages and applicability of traditional AC clamp ammeters were analyzed, and an AC/DC clamp ammeter for field calibration based on the Hall component DC compensation and a self-calibration technique was designed. The extended measurement uncertainty was evaluated. The relative uncertainty at all the selected AC/DC calibration points was within the range of 0.2% and the accuracy grade of the prototype was equal to and even better than 0.5 grades. The prototype was compared with traditional AC clamp ammeters through a test experiment. The results of the experiment indicated the capability of the designed clamp ammeter to make AC/DC measurement, which met the design requirements and showed its potential for application.
Abstract: Due to the limitation of the laser tracking technique in robot position and attitude detection, once the light is blocked, it cannot be detected. A laser tracking joint arm measurement system adopts the combination of a laser tracker and an articulated arm coordinate machine, and uses the principle of laser beam tracking and the high rigidity and flexibility probe of joint arm. It can detect and calibrate the robot's position and attitude. A laser interferometer and a length measuring machine were used to evaluate the system in different attitudes. The experiment results showed that the maximum error of the system was −0.042 mm at 2000 mm. The error at each point did not exceed ±（30+0.8×10−5L）μm.
Abstract: The luminous flux is an important index in evaluating the energy efficiency of a light source. Small luminous flux meters are a special instrument for measuring luminous flux parameters of light sources such as light emitting diodes and small bulbs. The accuracy of the measurement of the luminous flux directly determines the accuracy of the luminous flux value of a light source. Based on the characteristics of a small-scale optical flux meter, this paper studies and discusses two new calibration methods, namely, illumination method and radiation power method, by analyzing the principles of optical flux measurement and the traditional calibration method of luminous flux. Through the design of an experimental scheme and the establishment of a test platform, the experimental data are studied and analyzed, and the problems needing attention in measurement are summarized, which can shed light on the calibration of such instruments.
Abstract: In testing of the resistance of an insulator (resistivity higher than 109 Ω·m), the electrode added to it and the contact pressure and contact area between the electrode and the measured material are the key factors that affect the test accuracy. In this paper, the pressure-free sintering technique is used to prepare alumina ceramics containing certain manganese oxide, chromium oxide and silicon oxide components, and a self-made graphite sheet electrode is used to measure its resistance with an insulation resistance tester. The study found that the contact resistance with graphite electrodes is lower than that with silver electrodes. It was also found that the measured resistivity is basically stable, that is, the contact resistance is minimised, when the contact pressure between the graphite electrode and the alumina ceramic is not less than 19 N and the contact area is not less than 63.7 % of the material itself. It is concluded that silver electrodes can be replaced by graphite electrodes for accurate and easy testing of high resistance.
Abstract: This paper analyzes the requirements of allowable noise limits on civil and military aircrafts in design standards abroad , and compares them, especially those in standards of the U.S., with those in corresponding standards of China. By comprehensively comparing and analyzing the annual noise measurement process, data processing methods, noise evaluation standards and other indicators, this paper summarizes the problems such as insufficient coverage of the current military standards related to noise in China.
Abstract: This paper introduces several methods for measuring liquid refractive index with respect to the principles, accuracy and their applications. Among those methods, the femtosecond optical frequency comb is expected to make a major breakthrough in refractive index measurement in the future.
Abstract: The novel coronavirus (SARS-CoV-2) has a strong ability to infect, which has caused the pandemic. It has seriously affected human health and life, social economy and development. Fast and accurate detection of the novel coronavirus is particularly important for the diagnosis, prevention, and control of the epidemic. Chinese CFDA has registered 22 nucleic acid detection kits, which can meet the needs of high-risk groups for large-scale screening and effectively guarantee the prevention and control of the epidemic. Meanwhile, the novel coronavirus reference material, as a measurement reference, developed by the National Institute of Metrology, China further guarantees the accuracy and traceability of test results. This article analyzes the data published by the State Food and Drug Administration and the National Standard Material Sharing Platform, and combines relevant domestic and international research results to systematically review the novel coronavirus detection methods, test kits and reference materials, hoping to shed light on diagnosis, prevention and control of the novel coronavirus and other infectious diseases.