Abstract:Mass centre is an inherent characteristic parameter of objects. Centre measurement and calibration technology for mass is extremely important, especially in national defense area. Ballistic control and guidance of missile, safety and navigation of aircraft, attitude control of satellite, and mobility of armored vehicle are tightly associated with their mass centre characteristic. The present home and abroad development situation of the measurement and calibration methods of mass centre is described, advantages and disadvantages of these different methods are compared, and the future trend of the development is expected in this article.

Abstract:Resonant beam is a kind of widely used resonator. The axial load can be solved by measuring the resonant frequency of the beam, and the measurement purpose is achieved. The current frequency measurement method of resonant beam is not effective for dynamic circumstances and is restricted in many applications. In this paper, we focus on the problem of the frequency measurement of the double ended resonant beam, and propose a method based on Hilbert transform. Numerical method is used to solve the vibration equation of the resonant beam, and a variety of typical test signals are obtained. The simulation results show that the method can precisely obtain the frequency of dynamic signal.

Abstract:To solve the problems that traditional denoising methods are not suitable for processing the flight data recorder parameters which are of low sampling frequency, noise mixes with abnormity, nonlinear and nonstationary, a denoising method of flight data recorder parameters based on noise assisted bivariate empirical mode decomposition is proposed. Firstly, a complex signal constructed by given parameter and gaussian white noise is decomposed by bivariate empirical mode decomposition; secondly, according to the energy of each intrinsic mode function in imaginary part, the noise energy of each intrinsic mode function in real part is estimated; finally, the denoised parameter is obtained by dealing with each intrinsic mode function separately. Simulation results show that our method has more performance advantages than existing methods, and can improve the precision flight data recorder parameters denoising.

Abstract:The present study assesses the linearity of a FTIR spectrometry using the blackbody. The least square method is used for the data fitting to gain the linearity of the spectral response of the spectrometry. The conception of “spectral linearity” is adopted and the curve diagrams of the spectral linearity is obtained for the facilities of DTGS and MCT detectors, which reflects the spectral linearity characteristics and the influencing factors of the facilities. The detector, spectral range, and energy range which meet the requirements can be determined by the method, and the internal and external factors influencing the linearity can be shown by the diagrams. It is very important in the application.

Abstract:In order to ensure the verification period of power supply devices is scientific and reasonable, analysis and evaluation is made in this paper on the verification period according to the principle proposed by JJF 1139-2005 “Principle and Method for Determination Verification Period of Measuring Instruments”. The results show that the period of one year is reasonable.

Abstract:This paper mainly introduces a set for recurrence of the Pd-C high temperature eutectic point, which consists of a high temperature furnace, a temperature-controlling system, a pump, a gas protection system, a water-cooling system, a graphite crucible, a 2-class standard B-type thermocouple and a Pt/Pd thermocouple. The procedure of filling the crucible and reproducing the eutectic point are presented, and the experimental data are analyzed according to the recurrence results.

Abstract:Fiber grating technique has gained more and more applications in various fields with its rapid development. The wavelength reference is a very important part of fiber interrogator based on F-P, and it is a result of the standard in the interpolation. This paper mainly focuses on the characteristic and elements of the steady wavelength reference based on negative thermal expansion material ZrW2O8. Experimental analysis is done on its application in complete sets of instruments on account of the need of temperature changes.

Abstract:In order to make the electric locking accuracy test in air-to-air missiles within the framework of power gyroscope platform more real and intuitive, a new generation of the test system by using optical principle and CCD imaging is developed. The working principle and composition of the system are introduced. At present, the system has been validated in multi-types of infrared air-to-air missile test.

Abstract:A tripod is used to fix or support the photographing device or measuring instruments to keep it level, playing a supporting role in the stability of instruments. For the measuring instruments which supported by the tripod, the stability of the tripod is very important. Compared with the heavy base, the tripod is flexible and portable. Therefore, how to make the structural stability of the case on lightweight and portable equipment is particularly important. In this paper, we design a portable carbon fiber tripod which can support different types of laser trackers. The tripod can be lifted with small environment interference. In the case of 25 kg，the maximum deformation can be 0.01 mm by the torque of 2.5 N?m through the simulation analysis.

Abstract:This paper analyzes the similarities and differences of testing principles and structures between a calibration furnace of high temperature thermocouples and a tungsten tube furnace, focusing on researching the indexing method. Through the indexing experiments by B, PtRh40-PtRh20, Ir40Rh-Ir, and tungsten rhenium thermocouples and other high-temperature thermocouples in high temperature distinction, the correction value data of the system derived experimentally are listed and analyzed within the temperature range of 1500~2300 ℃ . The experimental results prove good reproducibility of the high temperature thermocouple calibration furnace. It can be used to calibrate all kinds of high temperature thermocouples within the temperature range of 1500~2300 ℃ in oxidizing and reducing atmosphere.

Abstract:In this paper, we design and implement a series of environmental tests, and obtain the numerical correction coefficients of spring tube type pressure gauges and digital pressure meters under different temperature and humidity environmental conditions. This paper provides the basis for using the calibration data at room temperature, provides a reference to improve the accuracy and reliability of the field pressure parameters measurement and calibration.

Abstract:This paper provides a new method for glass hydrometers from theory to practice . And the method can satisfy the verification for all kinds of hydrometers in all measurement ranges, including specification defined glass hydrometers that are within the range of 0.06～2.00 g/cm3 and the glass hydrometers that are beyond the range of 0.06～2.00 g/cm3.

Abstract:The gravity field for testing gravimeters is a standard device to calibrate gravimeters, and it mainly consists of gravity long baseline, gravity short baseline and dynamic calibrate field. The relative gravimeter is usually used to calibrate gravity short baseline and dynamic calibrate field, and also can be used to check equipment of gravity long baseline. Its technical performance must meet the requirements of testing gravity and measurement standards. The paper analyzes the repeatability, stability and uncertainty of CG - 5 relative gravimeters, as well as the consistency of results of multiple devices, and demonstrates the practicability of CG - 5 relative gravimeters to calibrate the value of gravity baseline.

Abstract:The difference between the condition of verifying or calibrating volt ratio boxes and the working condition is one of the main reasons for causing errors. This article introduces a simple method which uses 8508-1 digital multi-meter and 5720A multi-function calibrator to calibrate a BY22 standard volt ratio box in working condition.

Abstract:Through studying the operating principles of the vector network analyzer AV3620 , some common troubles and some maintenance methods are presented for its CPU, RF signal source and coupler to achieve maintenance of its key components.

Abstract:In the practical work, there is great demand for weights and the demand is very difficult to solve. This problem can be solved by the Replacement of Standard Weights which is suggested in the verification regulation of weighing apparatus. This paper deals with the issue on how to use the verification regulation reasonably so as to realize the replacement of standard weights in weighing instrument under the premise of satisfying the error theory.

Abstract:The proper procedures, correct methods and rules for rounding-off are presented in this paper for the reading of the test data of general pressure gauges and tyre pressure gauges. The method for rounding off the allowable errors of pressure gauges is introduced. The correct reading method for tapping displacement and return errors of pressure gauges is pointed out. Analysis is made on the quick determination method for deciding whether the pressure value errors are exceeding the allowable errors. The correct method for determining the deflection of the pressure gauge pointer is pointed out.