Abstract: Aiming at the problem of balancing the cost and accuracy in calibration of industrial robots, a low-cost three-dimensional high-precision contact self-calibration system for industrial robots was developed. The three-dimensional calibrator is installed in the end position of the robot (TCP). Using three orthogonal high-precision position sensors, the D-H parameters of industrial robots can be calibrated online with low cost and high precision by the calibration algorithm of D-H parameters of industrial machines and precise iterative measurement of a special four ball calibration table. A comparison with a laser tracker showed that the maximum En value of each measurement point was 0.63 and the comparison result was satisfactory.
Abstract: The instrumental neutron activation analysis has advantages including high sensitivity, no need for sample pretreatment, and a wide variety of measurable elements. It is one of the common methods for analyzing the element content of atmospheric particulate matter and can provide an important data basis for the analysis of pollution sources. This article summarizes the quality assurance process of each experimental process in the NAA laboratory using the relative comparison method and the single comparator k0 method to analyze atmospheric particulate matter samples, as well as internal and external quality control methods.
Abstract: Nucleic acid is the carrier of genetic information. With the rapid development of in vitro diagnostic technology based on nucleic acid amplification, nucleic acid detection is widely used in medical diagnosis, forensic identification, import and export inspection and quarantine, species evolution research, etc. Nucleic acid reference materials are a gold standard to ensure the accuracy and traceability of nucleic acid test results. Both the WHO and the Chinese Food and Drug Administration stipulate that in vitro diagnostic reagents need to use international and national reference materials or factory-level standards to guarantee the traceability and accuracy. The analysis of the carcinogenic mechanism of HER2, BRAF, EGFR and other gene mutations has prompted the listing of a series of targeted therapies such as trastuzumab, veilofenib, and rituximab, which has caused a large gap in Chinese nucleic acid reference materials. Due to the complex structure, easy degradation and large molecular weight of nucleic acid, it is difficult to meet the requirements of uniformity and stability. Therefore, development of nucleic acid reference materials is slow. This article briefly reviews preparation methods of nucleic acid reference materials and domestic and abroad research progress, for the efficient development of nucleic acid reference materials for in vitro diagnostics.
Abstract: To accurately evaluate the uncertainty in the calibration factor of a β-ray dosemeter, a traceable thin window ionization chamber was used to measure the reference dose rate at the reference position of the β-ray radiation field, and then the β-ray dosemeter was placed in the same position for measurement to obtain the indicated value. The calibration factor of the β-ray dosemeter was obtained, and the uncertainty in the calibration factor was evaluated. The main sources of uncertainty include the uniformity of the reference radiation field, the uniformity of the position in the measurement process of the substitution method, and the statistical standard deviation of the indicated value. The results show that in the calibration process, the uncertainty in the calibration factor can be reduced by improving the uniformity of the reference radiation field and the uniformity of the reference position.
Abstract: A QuEChERS sample pretreatment method coupled with gas chromatography-tandem mass spectrometry was established to determine 30 pesticide residues in Brassica oleracea. The results show a good linear relationship for the 30 pesticides in the concentration ranges of 50～250 μg/L, with correlation coefficients between 0.9966 and 0.9994. The average recoveries of this method were in the range of 77.46%～114.92% with the expanded uncertainty between ±0.0098 and ±0.0606. It provides a theoretical basis for determining the results near the critical point of the maximum residue in B. oleracea.
Abstract: The flow rate is the key parameter for evaluating the absolute efficiency of a hydraulic turbine. This paper reviews typical turbine flow measurement methods and studies the uncertainty evaluation for the ultrasonic transit time method. The total station was used to establish the accurate 3D model of the pipeline, and the geometric parameters were calibrated by measuring the relative position between the probe and the pipeline, then good uncertainty results were obtained. With a reasonable estimation of the ultrasonic transit time and flow rate integral modal, the uncertainty evaluation method for flow rates of super large calibers is given.
Abstract: In activities associated with measurement information management, institutions have accumulated a large amount of data in the process of digitalization of certificates and reports. The data are generally used to verify that calibrated parameters of instruments conform to legal requirements. The potential value of these data is often be ignored. This paper is concerned with mining the potential value of the measurement big data for value-added customer services. Methods of classification analysis, cluster analysis and association analysis are applied in this paper. It shows that data mining is an efficient method for digging measurement big data for social and economic benefits.
Abstract: In order to solve the problem of voltage conversion accuracy deterioration caused by transformer interturn capacitance, this paper analyzes the influence of parasitic capacitance associated with the winding of a transformer on transformer output misalignment, puts forward a method to eliminate or adjust parasitic capacitance influencing factor and resonant frequency point by combining theoretical analysis with circuit simulation, and proposes an equivalent negative capacitance generation circuit. An output comparison carried on an equal turn ration transformer before and after the improvement verifies the feasibility of the method.
Abstract: Optical measurement are often affected by low signal-to-noise ratios (SNR), resulting in larger measurement uncertainty. Measurement of the bidirectional reflectance distribution function (BRDF) in the near-infrared is particularly vulnerable to environmental interference due to weak infrared signals. The signal-to-noise ratio problem of optical measurement systems generally arises from detection systems. For infrared measurement systems, choppers and lock-in amplifiers are often used for weak signal measurement, but noise problems are also introduced at the same time. Therefore, this article focuses on the SNR of BRDF measurement in the near-infrared, aiming at the detector, chopper and lock-in amplifier, analyzing the source of noise, and proposing suppression methods and optimization measures to improve the signal-to-noise ratio. The optimized measurement system has improved anti-noise ability compared with that before optimization, and the repeatability has been improved from 2.1% to 1.6%.
Abstract: Aiming at the problem of pipe thickness measurement under high temperature in the petrochemical industry, this paper investigates factors affecting high temperature pipe thickness measurements based on ultrasonic spectrum, and develops an ultrasonic thickness measurement simulation system. In the simulation experiment, the influence of different thickness, different materials, different noise levels and different temperatures on the measurement results are discussed. In addition, the influence of different thickness measurement methods on the measurement of pipe thickness is compared. The experiment results show that the system can simulate the high temperature ultrasonic thickness measuring system and measure the high temperature pipe thickness.
Abstract: An acoustic laboratory of the Zhijiang Laboratory includes an anechoic room, a semi-anechoic room, a reverberation room and a listening room. Based on the overall layout of the experiment building, the internal structural dimensions of the acoustic laboratory were determined, and the acoustic performance design requirements were put forward, which can be used in the design and planning of similar acoustic laboratories. After the construction, the acoustic performance of the anechoic chamber, the semi-anechoic chamber, the reverberation chamber and the listening chamber was tested respectively according to national calibration specifications JJF 1147 and JJF 1143. The results show that the acoustic laboratory has achieved the expected specifications and it can provide a high-precision acoustic environment for acoustic research in the Zhijiang Laboratory.
Abstract: As an important measuring instrument in the trade settlement of heat measurement, the heat meter must ensure the accuracy and long-term reliability. Domestic heat meters have been put into the market with frequent quality problems, and some of them have been replaced by imported products. Although there are many problems in the use of domestic meters, they are ultimately attributed to poor long-term stability. This is reflected in the durability test, which is also the biggest and most important difference between domestic heat meters and European product standards in terms of technical requirements. This test establishes a study based on 4000 cycles of variable temperature test for domestic heat meters and compares it with the 2400 h+300 h test method, so as to realize the improvement and continuation of durability evaluation of domestic heat meter. It is the first time in China to realize comprehensive technical evaluation of heat meters under long-term application laboratory conditions, which contributes to improving the level of heat meter product quality in China, promoting the transformation and upgrading of the heat meter industry, and facilitating the heat supply metering reform.
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 clarifying the principle and steps of using angle mirror with laser interferometer and other mirror sets to complete the optical path adjustment. 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.