Abstract:Aiming at the difficulty of massive complex data analysis and processing in dynamic force measurement, the standard excitation sources, modeling methods of calibration instruments, dynamic time-frequency domain evaluation and measurement uncertainty evaluation on traceable measurement of dynamic force are systematically reviewed and discussed in view of principle and practicality. The importance of data modeling and evaluation in dynamic force calibration, value traceability and transmission of force are also illustrated. It provides a theoretical basis for the establishment of dynamic force measurement data evaluation mechanism.

Abstract:Microresonator frequency comb (MFC) is a tool for frequency measurement with high precision and integration potential. It will play a great role in deep space exploration and precise metrology. In this paper, the nonlinear optical generation and the device development of MFC are introduced. Especially, the status of application development of MFC including optical clock, range measurement, spectroscopy, optical-frequency synthesizer, low noise photonic microwave synthesis and coherent communication are elaborated. The future research hotspots and application prospects of optical frequency comb are predicted, which may promote the application development of optical frequency comb in metrology, measurement and communications.

Abstract:To solve the laboratory test problem of dynamic positioning performance of GNSS/INS integrated navigation terminal, this paper proposes a two-step method of GNSS / INS joint simulation based on the turntable inertial simulation test and satellite navigation simulation test technology. First the characteristic error model through the physical measurement of inertial sensor was obtained, and then the model was drived by using the carrier initial conditions and track data in the test scene to generate the analog output data stream of inertial sensor, and finally the GNSS signal simulation was synchronized to realize the process of GNSS / INS joint simulation. After compared with the field measurement, the simulation test results prove that the accuracy of the test data obtained by this method meets the expected indicators, the results are reliable, and the cost is lower and the efficiency is higher than other traditional test methods.

Abstract:When using the satellite navigation simulator to test the dynamic positioning accuracy of the navigation terminals, the test scene is generally a straight line or circular curve motion simply described by the motion equation in the coordinate system. There are problems of lacking randomness and irregularity in the test track, which is inconsistent with the actual application of the terminals, and the positioning track does not match the electronic map. This paper proposes to randomly and continuously select coordinate points on the road to plan the track according to the specific road in the electronic map, insert the changing speed and elevation with the derived track coordinate points, and create a dynamic scene of the simulator to test the terminals. The receiver terminal is tested by making an actual road dynamic test scene. The test results show that the dynamic positioning accuracy of the navigation terminal can be evaluated by using the irregular road track test scene with random coordinate points. The dynamic positioning deviation of the terminal is relatively large in a tight turn. By importing the standard track and the terminal track on the electronic map, the dynamic positioning track deviation can be visually displayed by matching the road. This method can be applied to dynamic positioning test of satellite navigation terminals combined with electronic map application, such as vehicle navigation instrument and wearable products.

Abstract:Aiming at the necessity to obtain the relationship between the output value of the pressure sensor and the loaded standard pressure value according to the metrological verification data when a pressure sensor is used in engineering measurement, the characteristic relationship between the output voltage of the pressure sensor and the standard pressure is analyzed by using the methods of normal test and variance analysis. According to the calculation results of correlation coefficient, a univariate linear regression model is established. The goodness of fit, linear relationship, regression coefficient and residual error of the univariate linear regression model are analyzed. The results show that the univariate linear regression analysis method can be applied to the fitting analysis of pressure sensor verification data in metrological verification, which has important reference value for metrological verification personnel to study other similar verification data fitting methods.

Abstract:The small thrust measurement research is performed to address the problem of small thrust values， difficult testing and inaccuracy of measurement generated by electric thrusters on micro-nano-satellites. The mechanism model of 5~100 mN torsional pendulum thrust frame sensing unit is established by using the principle of leverage and torque balance. The deflection performance under different thrusts is studied， and the linear relationship between deflection displacement and thrust is derived. The ANSYS simulation software is used to simulate the sensing unit and obtain the displacement clouds under different parameter conditions. The theoretical data and the simulation results are compared and analyzed， and the result shows that the structural design of the sensing unit is reasonable.

Abstract:Aiming at the reconstruction of explosion shock wave signal， the deep convolutional neural network （DCNN） was introduced to capture the local information and higher-order features of the shock wave signal， and the bi-directional long-term and short-term memory network （Bi-LSTM） was introduced to capture the time series dependence of shock wave overpressure data， and then the reconstruction model of explosion shock wave signal based on deep learning is constructed. The experimental results show that the reconstruction model of explosion shock wave signal constructed in this paper comprehensively considers the characteristic information of signal such as time sequence relationship， spectral characteristics and data variation law. In the pressure distribution reconstruction experiment of shock wave field based on finite measuring point data， the average errors of simulated and measured overpressure peaks are 3.53% and 13.71%， the average errors of positive pressure time are 7.35% and 14.26%， and the average errors of specific impulse are 4.02% and 11.92%， respectively. In the reconstruction experiment of shock wave pressure curve based on incomplete data， the missing values of simulated and measured signals are basically consistent with the original values， and the deviations are all around zero. All meet the requirements of explosion shock wave pressure reconstruction index. The research results have important guiding significance for signal reconstruction of explosion shock wave.

Abstract:In the atomic gravity measurement experiments, the linear chirp of the master and slave Raman lasers is achieved by a swept frequency source, which in turn compensates for the Doppler frequency shift produced by the atoms during free fall, thus enabling the measurement of the local gravitational acceleration g. Aiming at the problems of large volume and large heat generation of the traditional sweptfrequency source, this paper uses the AD9959 digital chip to implement a swept frequency source, which can be used as an atomic fountain frequency sweeping control and Raman optical phase-locked loop discriminating frequency and phase local oscillation reference. The final experiment shows that the phase noise of the swept frequency source is -112 dB@1 kHz, and the frequency stability is 1.38×10^-11@1 s. The effect on the sensitivity of the atom gravimeter is 2.81×10^-9 g/Hz^1/2, and the effect on the atomic gravimeter experiment is 1.15×10^-10 g within 600 s integration time. The system has the characteristics of low noise and high stability, and can meet the 10^-10 g resolution requirement of portable atomic gravimeter. The research results provide a certain reference for the development of atomic gravimeter from the principle prototype to the engineering portable experimental test instrument.

Abstract:Aiming at the problem of double closed-loop tracking control of dew point temperature in high-precision quartz resonant dew point meter, a temperature control system of resonant dew point meter based on double semiconductor cooler was proposed. The system uses STM32 as the main control chip and uses PID control algorithm to drive and follow the temperature of two semiconductor coolers through DAC. The temperature control system is tested in the temperature range of -15~15 ℃. The results show that the linear cooling rate error of the main temperature control system is no more than 10%, and the continuous linear temperature control precision is high. It can provide an effective temperature control solution for the high-precision quartz resonant dew point meter based on double cooling surfaces to realize double closed-loop dew point tracking measurement.

Abstract:A real-time processing system of large data volume based on FPGA is designed and implemented to address the problem of large amount of network test collection in the field of optical fiber sensing test. This paper introduces the hardware architecture and key module design of the system in detail， and focuses on the real-time processing method of large amount of data realized by FPGA through the peak-seeking module and the cross-reading and writing buffer module. The peak-seeking module is added to the FPGA to select valid data from a large amount of spectral data to reduce the amount of data transmitted， the continuity of data transmission is ensured through cross-read and write caches， and the filtered valid data are sent to the host computer. The practical application performance of the system is verified by experiments， and the results show that the system can effectively meet the data processing requirements of multi-channel optical fiber sensing demodulation based on spectrum acquisition.

Abstract:In view of the problem that the high overload environment and narrow test space of small caliber gun may lead to the failure of the chip， the shedding and fracture of the wire and solder joints of the projectile bottom pressure test system， the anti-high-overload research of the projectile bottom pressure test system was performed. The chip failure and isolation buffer mechanism model of the tester was established. The anti-high-overload performance of different mounting directions of the chip and different buffer materials were studied. The relationship between the chip's anti-overload capability and the installation direction， and the difference in the anti-overload performance of different buffer materials were obtained. The epoxy resin vacuum sealing method was proposed to solve the problem of shedding and fracture of wire and solder joint in high overload environment. Finally， the survivability and reliability of the projectile bottom pressure test system were verified by live ammunition test. The research results are of great significance to the design of the projectile bottom pressure test system for small caliber gun.

Abstract:In order to meet the requirements of high-precision non-contact measurement of nano-scale topography specimen, a high-resolution optical microscope probe is developed. Taking the laser holographic unit as the light source and signal pickup device, and using the differential spot size change detection principle,we have established a micro-displacement measurement system. Combined with the optical microscope imaging system, a high-resolution optical microscope probe is implemented. The probe has been integrated in a nano three-dimensional measuring machine to carry out the measurement experiments of step height specimens and one-dimensional line spacing specimens. The results show that the optical microscope probe combined with the nano three-dimensional measuring machine can realize the traceable measurement of nano-scale topography specimens, and it has the advantages of fast scanning speed, high resolution, compact structure and non-contact measurement. The development work has important practical value in solving the problem of nano-scale topography measurement.

Abstract:In order to verify the accuracy of the built-in relative-humidity conversion results of the precision dew point hygrometer,the internationally recognized Sonntag's saturated water vapor pressure formula and Hardy's wet air enhancement factor formula were applied to the dew point and relative humidity conversion formula, which was used as a standard conversion method to verify the built-in relative humidity conversion results of a variety of commonly used precision dew point hygrometers. The results show that the deviation between the displayed value and the calculated value of relative humidity is no more than ±0.03 %RH for the instrument with resolution of 0.01 ℃, and the relative humidity deviation of individual instruments with resolution of 0.1 ℃ reaches ±0.5 %RH. So it is difficult for an instrument with resolution of 0.1 ℃ to meet the requirements of a relative humidity standard. For the instrument without dew and frost point discrimination function, the results show that the relative humidity obtained by dew point and frost point conversion is very different, and it is also very different from the actual relative humidity, so it cannot be used for the measurement of relative humidity at negative dew point. The formula also results in the following conclusions: the enhancement factor has little effect on the results of the dew point and relative humidity conversion under normal temperature and pressure, which is negligible, but has a certain effect at high temperature and low pressure, which cannot be ignored.

Abstract:Bell-mouth flow tube is usually used to test the intake flow in aero engine tests. Aiming at the problem of the inaccurate measurement results and the increased measurement cost caused by the inaccurate layout of measuring points in the process of measurement, the velocity distribution on the measurement section of the inlet section of the tube is studied. The measurement principle of the bell-mouth flow tube and the flow state of the airflow in the tube under the turbulent flow state are analyzed in this paper. The variation of velocity along the diameter direction on the measurement section is studied, and the mathematical model of the radial velocity distribution in the tube is established. Finally, the velocity distribution model is analyzed and verified by the methods of experiment and simulation. A new method based on velocity distribution model is provided for accurately obtaining the air flow in the tube, that is, the data information of a few points on the measurement section of the flow tube is measured through the test to establish the velocity distribution model, so that a more accurate air flow value in the tube is obtained. The research results are of great significance to the measurement of intake air flow and the evaluation test of engine performance.