Abstract:Introducing the current research status in the field of dew?point temperature sensors, and expounding the principles and structures of optical, resonant, electrical, thermal, weight and chemical dew?point temperature sensors. It is pointed out that the optical dew point temperature sensor has high measurement accuracy, and the cold mirror dew point sensor can be used as the humidity measurement standard. The resonant dew point temperature sensor has the characteristics of small size, low cost, short response time, high sensitivity and good reliability. The electrical dew point temperature sensor has high sensitivity and low power consumption, which is convenient for miniaturization and integration. Gravimetric method is the most accurate absolute humidity measurement method and the basis for establishing humidity benchmark. Chemical methods are often used to measure organic gas mixtures in low humidity. The application of dew point temperature sensor in environmental monitoring, industrial manufacturing, medical diagnosis and other fields is discussed. It is pointed out that dew point temperature sensors will develop towards high precision, high stability and high response in the future, and their application range will be further expanded to meet the measurement needs in extreme environments.

Abstract:Introducing the significance and purpose of laser automatic frequency locking, expounds the algorithm of laser automatic frequency locking and common optical frequency references, analyzes the differences and advantages and disadvantages of different algorithms and frequency references, discusses the problems and methods to solve in the field of laser automatic frequency locking, and obtains the development direction and improvement trend of the current laser automatic frequency locking field. The areas to be strengthened are pointed out, and some difficulties to be solved are put forward, which provides a reference for the subsequent research on automatic frequency locking of lasers.

Abstract:To address the complexity and limitations of existing calibration methods for Scanning Probe Microscope (SPM), this article proposed a novel SPM calibration method by using a 2D micro?scale orthogonal lattice standard and peak detection (PD) method of the pitch center coordinates based on cross?correlation / convolution (CC) filtering of raster?scanned images. The geometric errors of motion include positional deviations Δx and Δy, straightness deviations δy and δx along x?axis and y?axis respectively, and the orthogonality deviation γ_xy between the two axes. The calibration factors C_x and C_y were calculated based on the number of pixels scanned on the x?axis and y?axis, scanning range, average pitch of standard grid metrology verification, and average grid spacing. Through case study, an AFM was calibrated using an orthogonal lattice standard with a nominal pitch of 10 μm, resulting in C_x and C_y values of 0.925 and 1.050, respectively, and an orthogonal deviation γ_xy of 0.015°. The expanded uncertainty of calibration for this AFM was 0.33 μm(k = 2.56). This SPM calibration method will promote the implementation and execution of SPM calibration standard documents, and has technical reference value for the development and performance evaluation of SPM instruments.

Abstract:This research is dedicated to the optimization of time delay processing for acoustic temperature measurement signals within engine combustion chambers, aiming to significantly enhance the precision and reliability of temperature determinations. A novel signal processing methodology is introduced, integrating wavelet packet decomposition transformation recombination with the isolation forest algorithm. This approach promises to refine the quality of temperature data by effectively mitigating noise interference and extracting pivotal information. Firstly, the acoustic temperature probe was thermally calibrated in a wind tunnel to obtain the data in a high temperature airflow environment. Secondly, the wavelet packet decomposition transformation and reorganization method combined with the isolated forest algorithm was used to filter and reconstruct the temperature data to eliminate noise and extract effective information. At the same time, outliers in the reconstructed data was detected to improve data quality and accuracy. The results of thermal calibration wind tunnel experiments show that the data distribution after signal processing is smoother and more symmetrical, the standard deviation is significantly reduced, and the data is more concentrated on the mean, so as to improve the accuracy and stability of temperature measurement. The research provides an effective technical solution for acoustic temperature measurement.

Abstract:In order to accurately measure in?situ hydrogen atoms during the combustion process of hydrocarbon fuels, this paper proposes a strategy for transient online detection of hydrogen atoms using a femtosecond?nanosecond laser co?excitation method. In this approach, hydrogen atoms in the ground state are excited to the 2S level through a two?photon process using a 243 nm femtosecond laser. Subsequently, these hydrogen atoms are further excited to the 3P level by a 656 nm nanosecond laser, and the fluorescence emission from the 3P?2S transition is detected, enabling interference?free transient online measurement of hydrogen atoms over a wide equivalence ratio range. Experimental results demonstrate that the femtosecond?nanosecond co?excitation method effectively reduces the interference of hydrogen atoms produced by laser photolysis on the detection of in?situ hydrogen atoms.

Abstract:In the load calibration experiments of wings with high aspect ratio, the wings will bend and deform with the increase of load, resulting in a change in the direction of the normal load at the loading point, which affects the accuracy of the load calibration experiments. To solve this problem, a set of high aspect ratio tracking loading device was designed. The device controls the vertical displacement of the loading point through an electric cylinder, and the horizontal displacement of the electric cylinder through a displacement table. The linkage control system is used to keep the force exerted on the wing surface in the load calibration experiment perpendicular to the wing surface, so as to ensure that the load on the wing is always in the normal direction. The comparison experiment between the tracking loading and the vertical loading was performed, and the results showed that the correlation coefficient of the data obtained by the tracking loading reached 0.999, which was better than the correlation coefficient of 0.976 obtained by the vertical loading of the weight, which verified the effectiveness of the tracking loading device. This device possesses the advantages of compact size and straightforward operation, thereby offering support for advancing the research on the performance of high aspect ratio wings.

Abstract:In order to solve the problems of a large number of pressure measurement equipment that needs to be calibrated, the scattered range, and the special and diverse kinds of media in the aircraft ground tests, this paper makes a theoretical analysis on the calibration principle and method of pressure measurement equipment, and designs an integrated pressure calibration device with multi?channel, multi?range and multi?media. The system has the functions of automatic control, acquisition and data processing. The calibration requirement of pressure measurement equipment for aircraft ground test has been practically solved, the calibration efficiency has been improved, and the application effect has been achieved.

Abstract:In order to more accurately reflect the sources of uncertainty in the measurement process of the rise time of step signals and improve the credibility of measurement results, numerical simulations and experimental analyses were conducted on the uncertainty components of step signal rise time measurement introduced by noise. The results indicate that the signal?to?noise ratio significantly influences the uncertainty of rise time measurements. In situations with low signal?to?noise ratio, the uncertainty in rise time measurements caused by noise becomes the main source. By comparing the application effects of the Savitzky?Golay smoothing algorithm and the moving average smoothing algorithm in the calculation of rise time for step signals, it was found that the use of an appropriate smoothing algorithm can reduce the uncertainty components introduced by noise, with the moving average smoothing algorithm showing better performance. This study contributes to improving the reliability and accuracy of dynamic signal measurement results, and is of significant reference value for uncertainty analysis in dynamic signal testing in the fields such as aviation, aerospace, and automotive industries.

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Abstract:This paper introduces the principles of the Rydberg atom microwave electric field sensor, elucidating the technical features of measuring the information of microwave electric field strength, phase, polarization, and frequency based on Rydberg atoms. Then it analyzes the current state of microwave full?information measurement based on Rydberg atoms and discusses the challenges faced by absolute self?calibration measurements and continuous broadband high?sensitivity measurements. It points out that measurement sensitivity enhancement and continuous broadband frequency measurement can be achieved through external field modulation. Various modulation and demodulation techniques are suggested to simplify phase and polarization measurements and data reading. The paper also explores the potential advantages to eliminate Doppler broadening effect by adopting multiphoton excitation in atomic vapor cell systems and adopting cold atomic systems to enhance microwave measurement sensitivity. It proposes the possibility for future exploration of such characteristics of Rydberg atoms as high orbital angular momentum states and strong correlations to further improve the performance of Rydberg atom microwave electric field sensors.

Abstract:Introducing the role of Coulomb's law and Ampere's law in the electrical system of units. According to the principle of equivalence between mechanical power and electric power, the current unit ampere（A） is selected as the basic physical unit. The practical unit system and electrical physical measurement standards are introduced. The principles of three quantum standards of electrical measurements and the ways for tracing to the natural constant are described. The role of vacuum permeability in the formulation of the Ampere's law is analyzed. The problem of the compatibility of an electrical quantum triangle with Ohm's law is explored. It is pointed out that the elementary charge constant is not simply derived from the Josephson constant K_J?90 and the Von Klitzing constant R_H?90, but is calculated from the fine structure constant formula. The principle of conservation of energy is the first principle in the system of units, and it is the link between mechanical and electrical measurement units. It is proposed that the displacement current between quantum dots has some influence on the single electron tunneling pump, the vacuum permeability is no longer an ideal constant, and the change of vacuum permeability will be the focus of later theoretical research.

Abstract:Introduced the theoretical model of laser feedback interferometry, explaining the technical characteristics such as high sensitivity, simple device structure, self?aligning, and the ability to achieve precise measurements of non?cooperative targets. The advantages of laser feedback measurement and traditional interferometric measurement methods were discussed. Explored various applications of laser feedback measurement in industrial and research domains, including displacement measurement, angle measurement, vibration measurement, and absolute distance measurement. It is pointed out that the use of structures like harmonic reuse, frequency reuse, polarization reuse, and full?path coherent combining can enhance the application performance of feedback measurement. Finally, the future development direction of laser feedback technology is discussed, providing reference for promoting the widespread application of feedback technology.