Abstract:

Abstract:

Abstract:A systematic review is conducted on the research progress of total temperature measurement and calibration technology for gas flow. High-precision, high-temperature, and high-frequency gas flow total temperature measurement methods, as well as steady-state and dynamic calibration techniques for temperature sensors based on calibration wind tunnels are summarized. The principles and applicable scenarios of various techniques are elaborated. The sources of errors in airflow total temperature measurement and the technical challenges in typical scenarios such as engines are analyzed. The development trend of total temperature measurement and calibration of gas flow under multi field coupling and extreme working conditions is explored. Constructive suggestions are proposed, including the integration of non-contact and contact measurement technologies and the enhancement of calibration capabilities under extreme conditions, which can provide reference and ideas for improving the accuracy of total temperature measurement in complex and extreme environments and supporting the high-quality development of aerospace and power systems.

Abstract:This paper systematically introduces the fundamental principles of traditional and single-photon LiDAR systems, and image fusion technologies. It provides an in-depth analysis of the feature disparities between traditional / single-photon LiDAR point clouds and visible images, as well as the associated image registration challenges. The study discusses the advantages and limitations of current registration methods, including calibration-based projection, feature matching, and deep learning approaches. Furthermore, it reviews the state-of-the-art in fusion technology for these modalities and explores its applications in fields such as target detection, recognition, and three-dimensional reconstruction. Looking ahead, the development of LiDAR point cloud and visible image registration necessitates research into methods capable of automatic adjustment and calibration during practical deployment. The application of more sophisticated neural network models is required to achieve deep multimodal information fusion, alongside further algorithm optimization to enable large-scale implementation. Regarding fusion technology, future work should focus on front-end collaborative design at the hardware level, adopt more advanced active sensing paradigms to enhance system efficiency and intelligence, and leverage advanced deep learning-based super-resolution networks to improve perceptual capabilities in complex environments.

Abstract:This paper summarizes and classifies the main technical methods for the combined measurement of linear and angular vibration. It reviews contact-based measurement methods using vibration sensors, as well as non-contact techniques such as Laser Doppler Vibrometry (LDV) and machine vision method, discusses typical applications of these me-thods in the synchronous detection of linear and angular vibrations, and analyzes their applicability conditions and technical limitations comparatively in terms of measurement accuracy, frequency response, and interference resistance. This paper further discusses future development trends in the combined measurement of linear and angular vibration. Future advances are expected to focus on two aspects for optimizing the combined measurement of linear and angular vibration: innovations in optical design and the integration of hardware with intelligent algorithms. In addition, a calibration system for the combined measurement of linear and angular vibration needs to be developed on the basis of absolute calibration using laser interferometry, so as to establish a complete traceability chain. Both contact and non-contact techniques are also expected to evolve toward greater system integration and scenario-specific customization to better adapt to the demands of complex operating conditions and practical field applications.

Abstract:Metrology and measurement serve as a fundamental technical basis for ensuring the safe, reliable, and efficient operation of low-altitude equipment, and play a key supportive role in promoting the high-quality development of the low-altitude economy. However, existing metrology and measurement technologies are unable to keep pace with the large-scale, complex, and intelligent evolution of low-altitude equipment application scenarios. This paper systematically outlines the new requirements for low-altitude safety metrology and measurement at the national and industry levels, summarizes the framework of the low-altitude metrology and measurement technology system, analyzes the current status of research on metrology and measurement standards for low-altitude equipment, and reviews domestic and international developments in low-altitude metrology and measurement. From the perspective of low-altitude industry growth, it identifies shortcomings and gaps in existing metrology and measurement technologies. This article looks forward to the development trend of low altitude equipment safety measurement and testing techniques, pointing out the need to establish a sound low-altitude equipment measurement and testing system, research specialized measurement and testing platforms and solutions for low-altitude equipment, improve low-altitude measurement and testing scenarios, and provide technical support for the high-quality, efficient, and sustainable development of the low-altitude industry.

Abstract:As the aviation manufacturing industry undergoes a digital and intelligent transformation, traditional inspection methods that rely on manual labor and paper records can no longer meet the stringent requirements for high efficiency, high quality, and high reliability in modern aircraft development. To solve this problem, this paper systematically studies the connotation, architecture, and element interrelationships of the digital system for aircraft development and testing. Based on an analysis of necessity and the presentation of an overall approach, a system architecture comprising three layers (foundation, support, and activity) and eight elements (organization, technology, process, etc.) is constructed, with a focus on the construction and interrelationships of core elements. Furthermore, an engineering verification scheme and implementation strategy are proposed. The research indicates that establishing a full-process, full-element, full-digital aircraft inspection system can provide an activity paradigm for integrating inspection into the mainstream digital aircraft development process, address the mismatch in inspection capabilities that constrain agile and efficient production development, and offer important insights for advancing the digital transformation of specialized inspection institutions.

Abstract:This paper introduces mainstream ultrasonic velocity measurement methods, and details the fundamental principles and calculation formulas of the transit-time method and the Doppler method. It focuses particularly on the ill-posed inverse problem inherent in ultrasonic velocity field reconstruction, and provides an in-depth analysis of the mechanisms, strengths, and inherent ill-posedness of classical inversion algorithms including the least squares method, Tikhonov regularization, and truncated singular value decomposition (TSVD). The paper summarizes key physical-signal joint processing strategies for mitigating significant ultrasonic beam drift and low signal-to-noise ratio (SNR). Prospectively, it proposes that the integration of physics-informed deep learning, computational fluid dynamics (CFD)-acoustics simulation coupling, and system-on-chip integration are core directions for advancing the technology towards high precision, adaptability, and miniaturization. This work aims to provide a reference for further breakthroughs and the engineering application of ultrasonic velocity measurement technology.

Abstract:To address the demand for rapid profile inspection of a large number of curved-surface components during aircraft assembly, the research team proposed an automated measurement method based on a laser tracking scanner. First, the coordinate systems of the measuring equipment and the measured object are aligned using the theoretical positioning points provided by the object model. Second, the measurement path of the equipment is planned according to the requirements of the measured curved-surface features of the object, and the complete feature data of the measured curved-surface of the object are automatically collected. Then, the measured data are finely aligned with the theoretical digital model for a second time. Finally, the deviation of the curved-surface profile is calculated. An experiment was conducted using a large-scale rotating paraboloid with a diameter of 4 meters. The results show that this method significantly improves the level of measurement automation. Compared with the traditional manual measurement method, the scanning efficiency is increased by approximately 30%, and the measurement results are consistent. This study provides strong support for advancing the development of high-efficiency geometric quantity inspection technology for curved-surface components of aviation equipment.

Abstract:In the field of periodic fatigue tests on metal structural components, existing data peak detection and correction methods suffer from low efficiency and poor adaptability in massive data processing. To address this issue, this study employs fiber Bragg grating strain sensors for the health monitoring of a metal structural component. Based on the data collected during fatigue tests, the problem of data errors caused by spectral distortion is resolved first. Subsequently, a peak data detection and correction method tailored for periodic fatigue test is proposed, which predicts peaks by utilizing the periodicity of data and achieves rapid detection and correction of peaks and valleys from the test data by combining frequency-domain analysis with statistical criteria. Comparative experimental results demonstrate that, compared with the sliding window extremum method, wavelet transform peak detection method, and K-nearest neighbors (KNN) density peak detection method, the method proposed in this paper exhibits higher detection accuracy and shorter processing time, enabling more effective data correction. This method provides strong support for efficient peak data detection and correction in the areas such as aircraft structural health monitoring and fatigue life evaluation.

Abstract:To accurately measure the high-temperature dynamic strain of hot-section components of aero-engines, this paper systematically investigates a high-temperature dynamic strain measurement method based on fiber optic sensing technology. High-temperature-resistant grating structures, inscribed using femtosecond lasers, were installed and fabricated on the substrate surface via plasma spraying technology. The performance of the sensors was tested and evaluated using high-temperature static and dynamic strain calibration rigs that simulate the operating conditions of hot-section components. Finally, validation was conducted through two aero-engine test rig experiments. The results from disk rig tests designed to assess high-temperature endurance and measurement accuracy demonstrated that the sensors could withstand environments up to 650 ℃, with a deviation of less than 5% between measured centrifugal strain and design simulations. The results from high- and low-cycle fatigue rig tests designed to verify dynamic strain measurement capabilities under blade vibration loads indicated a discrepancy of approximately 1.3% between measured and theoretical resonance frequencies, while the dynamic strain amplitudes were consistent with the predicted design magnitudes. The high-temperature dynamic strain measurement method based on fiber optic sensing technology provides important technical support for accurately assessing stress distribution and fatigue life of hot-section components in aero-engines and identifying danger points in advance.

Abstract:To address the limitation of traditional micro-ring resonator thermometry, which relies on tracking a single resonance peak, thereby restricting the measurement range to within the free spectral range, we propose a wide-spectrum microcavity temperature measurement method based on the matching of transverse electric (TE) and transverse magnetic (TM) mode spacing. A temperature measurement system was constructed, comprising a widely tunable laser, a silicon nitride micro-ring resonator, a Fabry-Pérot interferometer, and a water vapor absorption reference unit. Employing a two-stage calibration strategy that combines relative wavelength scale calibration with absolute wavelength anchoring, the system extracts the center wavelengths of resonance peaks and establishes a standard library of mode spacing values, thereby enabling temperature retrieval. Experimental results demonstrate that within the temperature range of -10℃ to 40℃, the mode spacing exhibits a strong linear correlation with temperature, yielding a coefficient of determination of 0.998. The measured temperature sensitivity for the TE single mode is 18.356 pm / K, while that for the TM single mode is 17.283 pm / K. The temperature measurement error of the traditional single resonance peak tracking method is ± 0.05 K, while the error of the microcavity broadband temperature measurement method based on mode spacing matching is ± 0.035 K. This approach not only improves measurement accuracy but also expands the measurement range, enhances system robustness and response efficiency, and provides important references for the engineering applications of microcavity photonic temperature measurement.

Abstract:The preparation efficiency and transfer fidelity between different traps are crucial factors limiting the practical application of ultracold atomic systems in quantum precision measurements. This paper presents an integrated solution to address two core issues: insufficient power stability of optical dipole traps during evaporative cooling, and decoherence induced by Majorana transitions during magnetic trap transfer. In the preparation stage, a dual-photodetector based optical power feedback stabilization system was designed and implemented, solving the power control challenge throughout the entire evaporative cooling process (especially in the milliwatt low-power regime) and suppressing power fluctuations to below 0.11% during critical phases, thereby achieving efficient evaporative cooling. In the transfer stage, precise control of the bias magnetic field in the quadrupole trap was employed to actively manipulate the position of the magnetic field zero, maintaining a safe distance between the ultracold atomic cloud and the zero point, effectively suppressing atom loss and decoherence caused by Majorana transitions. Experimental results demonstrate that after 6.8 s of evaporative cooling, ??Rb ultracold atoms with an atom number of approximately 3 × 10? and a temperature of 30 nK were successfully prepared and coherently transferred to a quadrupole magnetic trap for stable magnetic levitation. The preparation and transfer methods of ??Rb ultracold atoms provide key technical support for building reliable ultracold atomic sources for high-precision metrological applications such as atom interferometry and quantum gravimetry.

Abstract:To meet the demand for the precise measurement of ammonia (NH?), this paper proposes an ammonia concentration measurement technology using femtosecond laser filament-triggered discharge. Through long filament-triggered discharge formed in air by femtosecond laser pulses, the plasma emission spectra of NH? under different conditions were obtained by using a spectral acquisition system. The calibration curve for NH? concentration was obtained by utilizing the ratio of peak areas of characteristic spectral lines in the emission spectra. The one-dimensional spatial distribution of the spectral line intensity was analyzed. The research results demonstrate that the ratio of characteristic spectral line peak areas exhibits excellent linear response to NH? concentration, and the one-dimensional spatial distribution of characteristic spectral line intensities exhibits good stability. The NH? concentration measurement technology based on femtosecond laser filament-triggered discharge enables real-time quantitative ammonia measurement, providing a new method for real-time in-situ detection of NH?.

Abstract:To address the inherent limitations of traditional laboratory hardness testing methods, such as random sampling, result latency, and data silos, this paper proposes a digital online Brinell hardness testing method tailored for complex components, exemplified by aero-engine blades. The proposed method overcomes critical technical bottlenecks, including the precise positioning of irregular workpieces under dynamic conditions, adaptive constant-force surface grinding, and the high-precision recognition of low-quality indentation images in industrial environments. Consequently, a digital online testing production line was established, enabling accurate hardness measurement, real-time result evaluation, and full data traceability. Experimental results demonstrate that compared to traditional methods, the proposed approach increases measurement efficiency by a factor of four. Furthermore, the Measurement Systems Analysis (MSA) yielded a Gauge Repeatability and Reproducibility percentage (GR&R%) of 17.42%, with long-term operational performance consistently meeting requirements. By facilitating in-situ, real-time, fully automated, and traceable hardness measurement, this method provides a viable technical pathway for achieving the "integration of metrology and testing" within the context of intelligent manufacturing.

Abstract:The metrological standards of high-precision spherical coordinate scanning measurement systems are mostly limited to evaluating simple geometric features, making it difficult to meet the traceability requirements for full-field scanning accuracy of complex surfaces. Meanwhile, large curved surface standard devices face a bottleneck in maintaining high precision during calibrating high-precision spherical coordinate scanning systems due to the influences such as gravity and ambient temperature. To address the above difficulties, this paper proposes a calibration scheme based on large-scale physical surfaces. A large-scale combined standard device integrating concave, convex, and planar surfaces was innovatively designed to achieve comprehensive evaluation of the contour scanning performance of the measurement system. The proposed "segmented fabrication-precision assembly-thermal expansion release" structural design scheme utilizes an invar frame and an independently suspended thermal expansion release mechanism to suppress environmental thermal stress and gravity-induced deformation, enabling high-precision assembly of the large-scale standard device while ensuring long-term stability compliance. A high-precision reconstruction method for large-scale geometric digital models was developed to achieve accurate calibration of the high-precision spherical coordinate scanning measurement systems. Experimental results demonstrate that this method can control the assembly error tole-rance within 0.05 mm and reduce the RMS error to less than 0.01 mm, effectively supporting the establishment of accuracy traceability for the measurement system.

Abstract:Aiming at the problems in photogrammetric systems for aircraft static strength tests, such as the lack of applicable on-site calibration methods and devices, and the impact of complex on-site environments on measurement accuracy and efficiency, this paper proposes a multi-dimensional metrological calibration technique. A laboratory calibration device with a carbon fiber hexahedral frame was constructed to realize high-precision spatial coordinate transmission, with a measurement uncertainty U equals 1.6 + （L / 300) μm, k = 2. The influence of temperature and humidity (10 ~ 30 ℃, 10% ~ 90% RH) on measurement accuracy (maximum relative error 0.006 4%) was identified, and blue light illumination was adopted to eliminate light interference. A portable on-site calibrator was designed to break through traditional calibration limitations. Test results show that within the measurement range of 4.5 ~ 6.5 m, the system error does not exceed ± 0.3%, which meets the requirements of static strength tests and provides technical guarantee for the standardized application of the photogrammetry system in static strength tests.