Abstract:Micro-mass sensors can be used for the detection of poisonous gases and nanoparticles, which are widely used in environmental detection, medical diagnosis and other fields. In the past few years, micro-mass sensors based on graphene materials have been extensively studied because of their large surface area to volume ratio, low electronic noise, and excellent adsorption. This article focuses on a kind of ultra-high-sensitivity graphene micro-mass sensor based on the principle of resonance, focusing on the structure of graphene resonators, vibration pick-up schemes, quality sensitivity characteristics and other issues, and summarizes the graphene resonance micro-mass detection progress and challenges.

Abstract:Acoustic thermometry is widely used in daily life, medical research and industrial production, with great significance to broaden the application range of temperature measurement. In this paper, the acoustic thermometry methods are classified according to whether the sensitive element is in direct contact with the object to be measured. Also, this paper describes the basic principle, calculation formula and main parameters of ultrasonic internal thermometry, surface acoustic wave thermometry, sound-velocity thermometry and acoustic resonance thermometry respectively. Next, this paper introduces the main representative products, practical application and current application limitations of acoustic thermometry methods. By comparing and analyzing the precision problems and difficulties of acoustic thermometry methods, the conclusions and prospects are drawn, which can provide reference for further optimization and development of acoustic thermometry technology.

Abstract:Aiming at the intermittent and atypical sampling faults of the data acquisition system, a method is proposed based on sinusoidal excitation, introducing a fault-free expansion curve as the reference object, and using the stable measurement curve segment between different fault segment points and the corresponding expansion curve segment. The delay time difference is determined, and the fault recovery time is determined. Finally, the fault recovery time of each fault segment and the time interval of different fault segments are used for fault identification and characterization. The identification analysis and characterization results on the atypical fault curves actually obtained that verify the practicability and feasibility of the method described in this article.

Abstract:At present, there are some problems in the field of simulation calculation of the high altitude cabin exhaust system, such as the time-consuming of geometric modeling and the slow process of simulation. In order to solve these problems, according to the characteristic of the typical geometry structure of the high altitude cabin exhaust system, the parametric modeling scheme is adopted in this paper, the geometric model of the high altitude cabin exhaust system is formed by combining the parameterized models of the foundation structure. Through automatic grid division and numerical calculation of the geometric model of the exhaust system of the altitude cabin, the flow field and temperature field distribution data of the exhaust system of the altitude cabin are obtained, and are verified by comparison with the test results, the results show that the relative error between the calculated results and the test results is less than 3% , which meets the requirements of engineering practice. On this basis, advanced computer software development technology is adopted to package and customize the above analysis process, and combined with the secondary development technology of commercial software, finally, a parameterized simulation software package platform for the high altitude cabin exhaust system is formed. With this platform, a parameterized model of the high altitude cabin exhaust system can be built quickly, and the whole process of the exhaust system can be simulated quickly，and it has the advantages of high efficiency, convenience, accuracy, etc.

Abstract:Nuclear batteries were widely used in space exploration, nuclear industry and other fields. Because of the particularity of nuclear battery structure and materials, methods based on equivalent thermal power were often used when measuring their power. At present, the thermal power standard device used for measuring the nuclear battery thermal power measurement device in our country had the problems of low accuracy and poor stability. In order to solve the problems, this paper developed a set of standard heat source device. It consisted of a high-precision constant current source, a standard resistance, a standard heat source, an eight-and-a-half-digit digital multimeter, etc., which was based on the Joule effect of current and the principle of converting electrical energy into heat energy. It had been verified by experiments that in the range of current less than 3A, 0.7~147 W of power can be generated, and the relative expanded uncertainty was equal or less than 2×10-3 (k=2). It played an important role in ensuring the accurate traceability of the thermal power of nuclear batteries.

Abstract:The traditional measurement method of the sheet polarizer transmission ratio depends on the relative rotation of the polarizers, which is greatly affected by the light source polarization degree and the detector polarization-dependent response, and has a low measurement precision. To solve the above problem, this paper proposes a method based on Stokes vector analysis, by analyzing the polarization states change between the input and output light along with optimization algorithm, to extract the polarization parameters. This method has fast measurement speed, and is universal to the characterization of polarization optical elements used in flat panel display industry.

Abstract:There are defects of large measurement error, low operating efficiency and poor reliability in the traditional light calibration method of aircraft landing taxi lights. Aiming at this problem, this paper studies and proposes an automatic target calibration system for aircraft landing taxi lights based on the principles of laser collimation and laser ranging. The system uses a laser to simulate taxi lights to adjust the light path alignment. Laser ranging is used for the adjustment of the space position of the taxi light. the electronic target board is used to realize the automatic adjustment of the target board, and then the automatic calibration of the landing taxi light is realized. Carrying out actual experiments to verify the accuracy and reliability of the system, the results show that compared with the traditional method, the accuracy of the system for calibration is increased by 80%, the operating efficiency is increased by 60%, and it is not easily affected by factors such as environmental wind speed. It can effectively meet the calibration requirements of aircraft landing lamps and has important technical application value.

Abstract:In order to develop four-column force sensors with high dynamic performance, based on the Mechanism Analysis Method, stablished the natural frequency model of the four-column elastomer and mastered the design method to improve the natural frequency. The correctness of this method is verified by SolidWorks simulation and Standard Hammer Experiment. The results show that the natural frequency has a great relationship with the structural of four columns, and summarized the improvement methods of structural parameters conducive to improving the natural frequency of four-column sensor. Increasing the length parameter or width parameter of the cross section of the four-column sensor and reducing the height parameter of the four columns are conducive to improving the natural frequency of the four-column sensor.The results also point out that improving the material properties of sensor can also improve the natural frequency of sensor.Increasing the elastic modulus of the material of the four-column sensor, reducing the density of the material of the four-column elastomer can further improving the natural frequency of the four-column sensor.

Abstract:The non-contact measurement of gas pressure is an important research direction in the application of laser technology. In order to solve the problem of traceability in the process of gas pressure measurement, a pressure measurement method based on laser interference technology is designed. Through the theoretical research of the Lorentz-Lorenz equation, the gas state equation and the optical path difference equation, a pressure measurement model based on the optical path difference is established, and the pressure measurement problem is traced back to the optical path difference. With CO2 as the research object, a pressure measurement experiment system was built to carry out pressure measurement experiments with a pressure range of 1~3atm under the conditions of 293K, 313K, and 333K. The experimental results show that the pressure measurement value is in good agreement with the actual value, and the relative error is within 5%, which proves the correctness of the pressure measurement traceability model.

Abstract:If the location of CAN bus “carrier listening sampling point” is not set properly, it may affect the reliability of network data transmission in harsh electromagnetic environment. To measure the exact location of the sampling point, an error injection method is studied. This method is based on the error detection mechanism and the principles of CAN bus protocol, and the recommended range and value of sampling points in aviation and automobile industry standards. With this method, the principles of selecting test area is analyzed, a special test device has been developed and a verification test has been carried out. The device is used to test the sampling points of a certain type of CAN bus equipment, and the test results are analyzed under characteristic load conditions. This method realizes the high precision measurement of the location of CAN bus carrier listening sampling point, provides measurement support for improving the reliability of CAN bus network, and provides data base for reducing the tolerance of sampling points in the network.

Abstract:As a cooperative target in the measurement process of a transient high-speed laser velocimeter, the technical state of the grating surface determines the quality of the laser Doppler signal. Especially under the high-speed impact of the projectile, the internal structure of the grating is easily damaged, and the reflected light cannot be incident on the sensitive part of the detector. Therefore, this paper uses LS-DYNA simulation software to analyze the performance of the connection between the anvil structure and the grating structure, and obtain the stress and strain distribution at the surface, so as to provide a reference for the layout of the grating structure. Secondly, in order to achieve the purpose of correcting the optical path, through the selection and design of the incident lens group, the range of the optimal deflection angle is determined to be 5.2 degrees. This not only solves the problem of large error in the output result caused by beam deflection, but also provides a reference for the optimal design of the grating structure.

Abstract:Aiming at the calibration requirements of aircraft 270V DC power supply characteristic test system, combined with GJB 5189-2003 and other relevant standards, the calibration items and methods of the test system are studied. The calibration program is written based on LabVIEW platform, which realizes the functions of standard signal generation and acquisition. A calibration device is developed based on Direct Data Synthesis, broadband precision amplification and voltage divider. The calibration system is formed，which realizes the calibration ability of steady-state parameters and transient parameters. The field verification test program is prepared. The field test of power supply test-bed is carried out. The test results show that the function and technical indexes of the calibration device meet the requirements of the test system, which verify the rationality and effectiveness of the calibration method for aircraft 270V DC power supply characteristic test system based on broadband precision amplification and voltage divider. It provides an important guarantee for the accuracy, reliability and unity of the value in the development, production and maintenance of the 270V DC power supply system of the fourth generation fighter.