Abstract:In order to solve the problem of the residual noise of the probe light intensity in atomic magnetometer, a digital compensation method is proposed. Firstly, the basic theory of Larmor process detection is adopted, and the optical rotation angle of the linearly polarized light is detected through a photoelastic modulator and a lock?in amplifier. Then, the noise eater is used to obtain the compensation coefficient by sinusoidal modulating the probe light power and fitting the curves, and then the first harmonic component is post?corrected with the second harmonic component of the modulating frequency of the photoelastic modulator to realize the noise suppression of the probe light intensity. The hardware used for the amplitude modulation and even the primary light intensity stabilization device can be removed after obtaining the com? pensation coefficient, and the noise suppression can be achieved by using only the digital compensation technique. An atomic magnetometer based on K?Rb?21Ne vapor is bulit and carried out the experiment in the spin?exchange relaxation? free (SERF) regime, in which the results shows the noise of the optical angel detection signal is suppressed by 13.2 dB@ 3Hz. By applying the noise compensation method, the non?common mode noise caused by different optical paths is avoided, and the secondary stabilization is realized on the basis of the primary stabilization of the probe light in? tensity. The compensation coefficient can be calibrated regularly, and the influence from the change or instability of the system is reduced. The study is important for the sensitivity improvement of atomic magnetometers.

Abstract:La2Ce2O7 ceramics co?activated by Ho3+ and Yb3+ were synthesized by high temperature solid?state reac? tion. Both Ho3+ and Yb3+ substitute the La3+ sites in the La2Ce2O7 lattice, where the Ho3+ concentration is 0.05% at.% and the Yb3+ concentration varies in the range of 10% ~ 18% at.%. Pumped by a 980 nm laser, the up?conversion (UC) green emission peaked at 550 nm and the red emission at 666 nm were detected. When the doping concentration of Ho3+ and Yb3+ are 0.05% at.% and 14% at.%, respectively, the UC emission reaches the strongest intensity. Temperature sensing performance of La2Ce2O7∶Ho3+ / Yb3+ was studied in the temperature range of 303 ~ 483 K, the highest absolute sensitivity (Sa) is 0.002 8 K-1 at 303 K and the highest relative sensitivity (Sr) is 0.005 4 K-1 at 303 K. The results show that the ce? ramics La2Ce2O7∶Ho3+ / Yb3+ can be a potential candidate for remote temperature sensors.

Abstract:To solve the problems of difficulty in measuring the relative pose of the target spacecraft caused by differ? ent illumination, information distortion and incomplete feature of the image obtained by the visible light camera under complex lighting conditions in space, a binocular vision relative pose measurement method based on image enhancement and arc feature was proposed. An adaptive image preprocessing algorithm based on multi?scale Retinex with chromaticity preservation (MSRCP) was applied firstly to improve the image quality in the environment of spatial dim light and local strong exposure. Secondly, an ellipse detection algorithm based on the edge arc support line segment was applied to ex? tract the arc segment features of the docking ring on the surface of the target spacecraft and fit them into an elliptical con? tour. Finally, a binocular vision camera was used to build a physical simulation platform for relative pose measurement, and a binocular space elliptical conic measurement model was established to calculate the six degrees of freedom relative pose. The relative pose of target spacecraft was achieved in normal and dim light scenes at close range. The experimental results showed that the average error of relative position is better than 20 mm and the average error of relative attitude is better than 0.3° under normal lighting condition, and the average errors of relative position and pose are better than 30 mm and 1° , respectively, under dim lighting condition. The research results provide a reference for the identification and measurement of targets in on?orbit service missions such as close?range space rendezvous and docking, and have techni? cal reference value.

Abstract:To address the failure of existing satellite video stabilization algorithms in no?control?point scenarios, a satellite video stabilization algorithm based on multiple moving targets is proposed. This algorithm constructs a framework that integrates target detection, trajectory smoothing, and norm optimization by combining multi?target Kalman filtering, rlowess trajectory smoothing, and L1?L2 norm optimization, ultimately achieving satellite video stabilization. Experiments were conducted using a maritime multi?target ship observation dataset. The results validate the effectiveness of the algo? rithm, showing that the stabilization error of the proposed algorithm can be controlled within 0.3 pixels in both the X and Y directions. This study fills the technical gap in satellite video stabilization in no?control?point scenarios and has broad and significant engineering application value.

Abstract:In order to solve the problem that the static moments of composite paddles are widely varied and it is difficult to make an accurate qualification evaluation, the static moments of multiple sets of paddles are investigated by using the control variable method according to the basic theory of the balance. By analyzing the differences caused in the experimental data and considering the accuracy of the measuring equipment itself, the main factors that have a greater impact on the measurement are discovered with quantitative analyses and calculations. Through comparative experiments, it is proved that the greatest influence on axial torque measurement is the distance of the positioning surface from the measuring cutter and its flat machining accuracy. The greatest influence on radial torque measurement is the angular measurement accuracy of the specific section of the propeller blade. This study provides a theoretical and data basis for process optimization for subsequent propeller design, production and maintenance, and is significant for the research and development of new propeller blades in the future.

Abstract:In order to break the limitation of traditional measurement guarantee that only focus on the accuracy of measuring equipment rather than the reliability of measurement results, a measurement process control management system suitable for the full link of civil aviation engines has been constructed. The system is designed to improve the quality of measurement data, covering the entire product measurement processes from component design to overall test, from airworthiness certification to customer delivery. In the measurement process design stage, according to the measurement requirements and the degree of importance of the process, the measurement capacity is analyzed, and the measurement quality requirements, namely measurement uncertainty, are derived. In the measurement process control stage, according to the results of uncertainty analysis, the sources of uncertainty are identified, and the measurement process is monitored by means of measurement system analysis (MSA), control chart, and measurement capability audit. In the measurement validity verification stage, combined with the characteristics of aero?engine measurement process in scientific research stage, a same family measurement process collection is established, and quality verification is achieved through the measurement uncertainty evaluation. The system was initially applied to the measurement classification, capability analysis, process monitoring and result verification of the project "high?pressure compressor rotor assembly" during the assembly execution process in the factory, which has a reference significance for establishing the measurement process management of all relevant parties in the process including test verification and manufacturing.

Abstract:A data perception and visualization application system for workshop discrete measurement equipment is established to solve the problems of scattered distribution of measurement equipment, difficulty in unified collection of measurement data, low utilization rate of measurement data, and high cost of equipment post maintenance in industrial manufacturing workshops. By building a data conversion protocol repository, multi?protocol communication compatibility for various types and brands of measuring equipment can be achieved, and the problem of unified data collection and cen? tralized management of the discretely distributed equipment can be solved. The data conversion protocol repositories are integrated in client software, which has such advantages as low cost, easy deployment, and convenient protocol expansion. The system combines data analysis and visualization technology to perceive real?time changes in workshop measurement equipment data, providing managers with intuitive and clear display of data and analysis results. The system realizes real? time collection, analysis and processing of measurement data, improves data utilization efficiency, and provides important guarantees for production decision?making. The visualization analysis function of the system can help managers quickly understand the working status of workshop

Abstract:This paper makes a detailed introduction to the measurement principles of the optical surface absolute de? tection methods such as three?plane (spherical) mutual detection method, bispherical method, rotating average method, translational difference method (pseudo?shear interference method), parity function method, random ball method and rota? tion?translational method. It also describes the development status of absolute detection methods at home and abroad, and discusses the application fields of each absolute detection method and the corresponding technical limitations by compari? son. Then it makes prospects to the future trends of absolute detection technology from both physical implementation and algorithmic perspectives and proposes to increase the absolute detection accuracy of surface shape by improving the accu? racy of external mechanical structure. Finally, it analyzes the advantages of deep neural network algorithm and computa? tional optical imaging technology in the absolute detection process, and proposes that the absolute detection accuracy of optical surface shape can be further improved by combining the two technologies with the absolute detection methods. It can provide a useful reference for the research of absolute detection.

Abstract:This article introduces the concept of structural health monitoring (SHM) technology and the principles of active and passive damage monitoring methods, and analyzes the current research status of structural health monitoring technology for aircraft both domestically and internationally. It elaborates on the monitoring principles and applications of advanced sensor technologies such as comparative vacuum monitoring (CVM) sensing technology, intelligent coating sen? sor technology, fiber optic sensing technology, piezoelectric sensor (PZT) technology, and wireless sensor network (WSN) in various types of equipment. Typical applications of SHM technology on the F-35 joint strike fighter (JSF) are pre? sented. It is pointed out that aircraft SHM technology is developing towards intelligence. In the future, it is necessary to fo? cus on the intelligent diagnosis technology of sensor networks, SHM technology in complex environments, health manage? ment technology based on SHM technology, health monitoring technology for intelligent materials or structures, and to ap? ply frontier technologies such as deep learning and digital twins to the aviation field to promote the development of air? craft structural health monitoring technology in China.

Abstract:Elaborating on the definitions of coaxiality between mechanical structures, coaxiality between optical axes, and coaxiality between optical axes and mechanical axes. It introduces the principles and advantages and disadvan? tages of coaxiality measurement methods for mechanical structures, such as extensometer coaxiality measurement method, strain gauge coaxiality measurement method, dial gauge coaxiality measurement method, coordinate measuring machine coaxiality measurement method, laser alignment instrument method, etc; Analyzed the characteristics of optical axis coaxiality measurement methods such as interference comparison measurement, reflective centering measurement, and di? rect transmission measurement; This article introduces the principle and application of a coaxiality measurement method between optical and mechanical axes based on image processing and machine vision technology. It is pointed out that the measurement method for coaxiality between mechanical structures is relatively traditional, which has disadvantages such as low measurement efficiency and the need for human judgment; Coaxiality measurement technology will develop to? wards high precision, automation, and non?contact.

Abstract:To address the issue of data loss commonly faced by tip timing systems in practical applications, a method for identifying missing tip timing data based on Correntropy Matching Pursuit is proposed. This method uses Correntropy Induced Metric based on Gaussian kernel functions to measure sample weights. Unlike orthogonal matching pursuit, which assigns the same weight to all observed data, Correntropy Matching Pursuit assigns weights of different norm types to the observed data based on changes in correlated Correntropy Induced Metric, making it more robust to outliers. The performance of this method was verified through simulations and experiments. The results showed that the correntropy weight factor assigned nearly zero weights to the missing data locations, effectively reducing the impact of data loss on fea? ture extraction results, thus demonstrating the robustness of the method. The tip timing data loss identification method based on Correntropy Matching Pursuit provides a theoretical basis for the implementation of tip timing systems in practi? cal applications.