Abstract: Accurate measurement of kinematic parameters of targets by environment-sensing sensors is the basic requirement for safe and efficient driving of intelligent connected vehicles. Among existing mainstream commercial vehicle-borne radar sensors, 24 GHz and 77 GHz millimetre-wave radars are different in speed, distance, and angle measurement performance because of their different working frequency bands and bandwidths. In order to evaluate the speed measurement performance of 24 GHz and 77 GHz millimetre-wave radars, we developed a simulated calibration facility for kinematic parameters of millimetre-wave radar targets based on the virtual instrument technique, and verifies The feasibility and the speed simulation accuracy of the simulated calibration facility were verified using simulated speed calibration results of 24 GHz and 77 GHz millimetre-wave radar samples. The results of the simulated calibrations and comparison of the uncertainty evaluations showed that the speed measurement repeatability and accuracy of the 77 GHz millimetre-wave radar sample are superior to that of the 24 GHz millimetre-wave radar sample.
Abstract: The absolute measurement of laser power mainly adopts an electrical calibration laser power measurement system, which traces the laser power to the voltage and standard resistance reference to achieve the value realization. For absolute measurement of high power lasers of 10,000 watts level, the damage resistance of the absorber is the key to the measurement system. In this paper, the design and damage-resistant performance of an absorber of 10 kW electrical substitute laser power meter were studied, and the damage-resistant laser absorber cavity was designed and developed based on the reflective beam expander structure and water cooling method. The heat transfer characteristics of the absorber under different laser power, spot size, and cooling water flow rates were studied using numerical heat transfer analysis. The results show that the temperature rise of the laser absorption surface is well controlled, and the upper limit of the power measurement of the absorber reaches 15 kW, which is mainly limited by the vaporization of cooling water caused by the surface temperature rise of the water cooling channel. The results of the numerical analysis are essential for the clarification of the damage resistance, the setting of the measurement system parameters, and the optimization of the absorber structure. Under the condition of a high-power laser, the electrical calibration measurement system with the absorber was tested. The maximum measurement power reached 14.3 kW, and the measurement data remained stable at different powers without damage to the absorber.
Abstract: This paper presents the influence of reversibility on uncertainty of force measurements. In actual measurement, the coverage factor k of reversibility cannot be determined because of its unknown distribution, despite of the value of 1.732 defined in ISO376. The reversibility properties of force sensors are studied based on the definition of coverage factor. Using both discrete and continuous analyses, the actual distribution of reversibility are discussed and finally the coverage factor k is determined. The discrete random variable is transformed into a continuous one by estimating the kernel density. Then the probability density of the unknown distribution is simulated using the center method and the shortest coverage interval. The finally determined coverage factors corresponding to confidence intervals of 95% and 99% are 1.8463 and 2.2216, respectively.
Abstract: In recent years, due to national policy and local support, the new energy vehicle industry has developed rapidly, and pure electric buses have become more and more popular in the market, and the frequency of appearance in real life has also increased. To ensure vehicle performance and personnel safety, on-site installation and debugging is particularly critical, which requires relevant practitioners to have a certain knowledge base and practical hands-on ability to check the installation and collect CAN messages using the vehicle to troubleshoot potential problems and ensure that the vehicle is stable in operation. This paper discusses and analyzes the five aspects of low-voltage power testing, communication testing, high-voltage testing, dynamic testing, and NVH testing based on the experience of working in debugging vehicles, and analyzes and discusses the problems that exist in the debugging process of pure electric buses to ensure that pure electric vehicles can operate safely, reliably and comfortably.
Abstract: High-voltage instruments and equipment in the use of the process will produce high-voltage industrial frequency electric field risks to human health, and measurement personnel in the measurement of such instruments and equipment often need to be close, long exposure to high-voltage industrial frequency electric field. This paper selected a high-voltage test transformer as the object to be tested. By constructing an analysis model and formulating a detailed test plan, a high-precision field strength meter was used to determine the power frequency electric field strength of the test transformer in the measurement process, Combined with related national standards and mathematical models, this paper proposed a variety of suppression and shielding schemes, compared the effects of different schemes through experiments, and proposed relevant measurement safety protection suggestions.
Abstract: By comparing the measurement results of viscosity oil standard and viscosity silicone standard on different types of viscometers, as well as the viscosity-temperature characteristics and surface tension characteristics of the two viscosity standards, the differences between viscosity oil standard and viscosity silicone standard are discussed, which provide a reference for the practical use of the two viscosity standard solutions.
Abstract: The process of the Chinese aqueous solution acidity (pH) primary standard participating in three international comparisons of carbonate pH measurements is briefly described. A systematic error in the benchmark was found in the 2006 CCQM.K18 and 2007 CCQM.K18.1 comparisons. It was concluded that the negative systematic error was caused by the continuous drift of the electrode potential due to the structure of the primary standard’s Harned-Cell and the low equilibrium potential obtained by using slope inversion. In 2009, the pH primary standard device was modified and improved with a new Harned-Cell structure, and in the international comparison of APMP.QM-K18.2016 in 2020, the international equivalence agreement was achieved, and the degree of equivalent DoE(di, U(di)) was DoE(−0.0014, 0.0030) .
Abstract: The National Metrology Data Center has developed a metrology information data push system. The system first uses the web crawler technology to capture the latest metrology information data from authoritative metrology websites at home and abroad. Then the data is integrated to a three-dimensional topic map after being preprocessed by AI and manually curated, which is further published to the website and pushed to the corresponding subscribers with corresponding subject terms. Researchers can subscribe to the information according to the three dimensional topic maps or custom subject terms to obtain the latest metrology information data in real time. The system has been deployed on the website of the National Metrology Data Center, and the actual operation is good, which verifies the feasibility and development potential of the program.
Abstract: The effective emissivity of the blackbody cavity is a key characteristic of the blackbody radiation source for ear thermometer calibration and verification. The emissivity characteristics of the blackbody cavity recommended by the ear thermometer calibration protocol are presented, and brightness temperature comparison experiments are conducted with the blackbody cavities of two international standards recommended for ear thermometers. Based on the data analysis, an evaluation of the three ear thermometer blackbody cavities is given.
Abstract: By investigating the energy measurement management of 12 data centers in Beijing, this paper focused on the main factors affecting the accuracy of calculating the power usage efficiency (PUE) of data centers, analyzed the common problems in calculating PUE, and proposed to use the management method of energy measurement to regularly compare measurement instruments to determine their accuracy, and improve the accuracy of data center PUE by the management of measurement on different usage, classification and district measurement
Abstract: Based on the study of the OIML Certification System (OIML-CS), this paper expounds on the implementation of the OIML-CS in China. The practice shows that China as a major country in the manufacture and use of measuring instruments actively carries out and implements the OIML-CS, which is conducive to promoting the dual improvement of the measuring instruments quality and the legal metrological supervision ability, and is of great significance to the development of China's measuring instrument industry.
Abstract: To improve detection efficiency, a study on automatic detection for dental X-ray machines was completed by summarizing quality control standards. The study is based on the DigiDent module, and for high contrast resolution, the algorithm of line pair spacing based on wave crest and trough and the algorithm of angular deviation based on measurement line translation are proposed; for low contrast resolution, the algorithm of half-peak full width combining waveform mean and standard deviation is proposed. The experiments show that the relative deviation of the automatic detection results is controlled within ±5%, which meets the detection requirements.
Abstract: In the verification of the acidity meter, it is required to verify the indication error of standard solution measurement and that caused by temperature compensation in a constant temperature environment. To avoid the low verification efficiency caused by the repeated heating and cooling of the traditional thermostatic cell, and to realize the rapid on-site verification, this project has developed a multi-point thermostat standard device based on the principle of independent thermostat control of small volume and multi-unit, using semiconductor chilling technology and PTC heating technology with PID digital adjustment technology, which is light in weight and can provide multiple thermostat standards simultaneously. The temperature uniformity of the device is less than ±0.1 ℃ and the temperature fluctuation is not more than 0.2 ℃, which can meet the needs of acidity meter field test or calibration.
Abstract: To address the potential photobiological safety risks to humans during the use of iris scanners, two measurement methods, broadband radiance measurement and spectral radiance weighted measurement, were used to measure the radiation luminance of the retinal thermal hazards caused by micro-visual stimuli of iris scanners, and the results obtained by the two methods were analyzed and compared to derive the applicable measurement conditions for each of the two methods.
Abstract: The calibration method of Volatile Organic Compounds for Continuous Emission Monitoring System (VOCs-CEMS) was studied under working conditions, and two reference methods of air-bag method and portable monitoring equipment were used to compare and analyze the measurement results with VOCs-CEMS. The results proved that the portable monitoring equipment is more accurate, faster, and more reliable than the air-bag method, and can meet the calibration requirements of VOCs-CEMS under working conditions.