Abstract:The practical problems in tracing and transferring the value of the plumb alignerare discussed in detail, including the lack of high-accuracy calibration device for the plumb aligner, the error of gravity line sensor of the plumb aligner itself, and the difficulty of ensuring the accuracy of the laser plumb aligner. The relationship between the gravity line and the plumb line is analyzed in detail, and the reasons why the plumb line is different in different geographical positions are explained. The idea to solve the problem of the traceability and transmission of the value of the plumb aligner is expounded.

Abstract:General verification rules or calibration specifications only check and calibrate the comprehensive errors or hardware indicators of portable coordinate measuring instruments, but do not verify the correctness of their software functions and algorithms. According to the requirement of management and control in practical work, this paper analyzes the importance and difficulty of software verification and validation, and puts forward a simple and easy-to-operate software validation method based on algorithm comparison and equipment comparison, which is suitable for internal measurement and testing organizations in enterprises. The validation process and validation results are described concretely through a software validation example of laser tracker.

Abstract:In order to study the mathematical model of Venturi flowmeter under transient flow, the flow field of Venturi flowmeter under step flow was simulated by FLUENT software. The discrete values of flow and differential pressure under different step flow conditions were obtained. The coefficients of differential equation were obtained by plane fitting method, and then the mathematical model of Venturi flowmeter under transient flow was determined.

Abstract:In the vacuum heat treatment unit, the traditional quadrupole mass spectrometer (QMS) has the problem of inadequate residual gas detection due to structural defects, and the connector between the standard vacuum gauge and the vacuum gauge to be calibrated also has low vacuum detection efficiency due to structural problems, which leads to the inaccurate measurements of vacuum degree and residual gas in the large-capacity vacuum furnace. This article starts with TRIZ theory to make an asymmetric optimization of the structure of QMS, and transforms the T-shaped structure into a spherical structure and improves the heating and pressure control. The efficiency of vacuum heat treatment measuring device has been improved by the optimization and improvement.

Abstract:The piezoelectric tuning fork is combined with tungsten probe to form a scanning probe of SPM. The double probe is symmetrically placed at the equatorial circle cross section of the microsphere to form a microsphere sphericity differential measurement system. The dual probes are roughly aligned by a visual guidance system. The microsphere and probes are focused by video microscopy, and multiple groups of photos are taken. Then the aligned images are processed by wavelet analysis edge detection and multi-image fusion, and the image processing results are fed back to the system for accurate alignment. In the actual experiment, the measurement results of the equatorial circle cross section of the microsphere under the alignment method are obtained, and the influence of alignment error on the system measurement results is analyzed.

Abstract:In order to solve the calibration problem of high-pressure hydraulic oil flowmeter for civil aircraft, a high-pressure hydraulic oil flow standard device is developed. The standard device uses a high-pressure plunger pump to provide flow source. The flow rate and pressure of the flow device can be adjusted in a wide range by means of frequency conversion speed regulation and proportional control valve. A piston-type volume tube is used as the main standard in the standard device to realize the flowmeter calibration under high-pressure conditions. The calibration test of cylindrical gear flowmeter under variable pressure condition is carried out by using this standard device. The difference between the flowmeter coefficients under high pressure condition and atmospheric pressure condition is more than 5%, which proves the importance of the research on flowmeter measurement performance and correction method under high pressure and variable pressure. The establishment of this standard device provides an effective means for flowmeter calibration and measurement performance research under high pressure, and it has practical value.

Abstract:The multi-degrees-of-freedom vibration table lacks a convenient and effective method to measure the multi-degrees-of-freedom vibration at present. This article discussed the six degrees of freedom vibration testing method based on the acceleration sensor, and proposed an accelerometer array configuration based on four three-direction accelerometers. The motion state of the configuration is theoretically deduced according to the six degrees of freedom motion system equations, and the specific packaging method is designed. Finally, the encapsulated accelerometer array configuration is verified by the multi degrees of freedom vibration test. The test results show that the proposed accelerometer array configuration based on four three-direction accelerometers can test and restore the angular acceleration. The method is simple and reliable, and can be used for multi degrees of freedom vibration test. It is expected to be widely used in on-site vibration measurement and calibration.

Abstract:In order to calibrate the crest factor of the aircraft power supply characteristic test system, and to ensure the accuracy of the test results of the system, the programmable power supply and related hardware equipment were used to generate the specified crest factor. By analyzing and studying the common methods of time domain and frequency domain for generating AC voltage signals with specified crest factor, a parabolic fitting method was proposed to generate AC voltage signals with specified crest factor. Through the actual measurement analysis, it is verified that the parabolic fitting method has higher accuracy, and is more suitable for calibrating the crest factor of the aircraft power supply characteristic test system.

Abstract:In practical applications, the fuel flowmeter will work in unsteady flow state, and the measurement performance of the flowmeter may change. Using the dynamic fuel flow standard device, the unsteady flow tests was performed on the Coriolis mass flowmeter and the volumetric scraper flowmeter. The influence of unsteady flow environment on the measurement results of the two kinds flowmeters is analyzed, and the use and calibration of recommendations are given.

Abstract:Taking the cylindrical gear meter that is used as master flow meter as an example, several typical flow calculation methods for the master flow meter used in the non-fixed point in the standard flow facility by master meter are introduced, and the uncertainty of each flow calculation method is evaluated. The comparison of the examples shows that using the least squares fitting calculation and selecting the fitting order matching the characteristics of the flowmeter can reduce the uncertainty introduced by the algorithm obviously, the method of selecting the flowrate correction value to calculate the flow rate is relatively inefficient for the low flow range, and the uncertainty introduced by using the meter factor is relatively close with that introduced by using the flow rate correction coefficient.

Abstract:The diameter of straight pipe is not usually exactly the same with the diameter of turbine flow-meter, which effect the K-coefficient of the turbine flow-meter. By choosing CL series and LWGY series turbine flow-meter, the calibration test ,the impact of different diameters of upstream and downstream straight pipe, is carried out on the dynamic fuel flow standard device. The experimental results show that the error introduced from straight pipe can not be ignored, therefore, the use or calibration of turbine flow-meter is required diameter of straight pipe is consistent with the flow-meter.