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Abstract:

Abstract:This paper introduces the role of atomic vapor cells in hot-atom precision measurement systems and discusses the principal physical mechanisms governing atomic spin relaxation, as well as their effects on polarization lifetime, coherence time, system noise, and long-term drift. The processing characteristics, applicable scenarios, and development trends of conventional glass-fabricated vapor cells and MEMS-micromachined vapor cells are compared. The effects of material selection, structural design, wall-surface treatment, buffer-gas metering, and thermal and magnetic environment management on vapor-cell performance are also analyzed. Looking ahead, the development of atomic vapor-cell processing and manufacturing should focus on establishing an engineering-oriented characterization and evaluation framework based on intrinsic parameters, including atomic number density, spin polarization, and relaxation time, together with the performance requirements of representative application systems. Key error sources should be controlled at the stages of vapor-cell design, fabrication, and evaluation. By establishing the underlying physical correlations between manufacturing parameters and device performance, atomic vapor cells can be advanced toward standardized devices with reproducible performance, predictable service lifetimes, and compatibility with large-scale production.

Abstract:To further promote the development and application of domestic laser trackers, this paper systematically introduces the laser tracker technology and the independent research and development progress of laser trackers achieved by the research team at the Institute of Microelectronics of the Chinese Academy of Sciences (IMECAS). The basic principles and structural components of laser trackers are elaborated, and key techniques including laser ranging, miss-distance detection, precision angle measurement, servo tracking, error compensation and calibration are analyzed in depth. The current domestic and international testing specifications and technical standards in the field of laser trackers are presented, performance evaluation methods for laser trackers are discussed, and approaches to improve laser tracker performance are analyzed from both theoretical and application perspectives. The typical applications are introduced, such as in-situ intelligent manufacturing, real-time dynamic robot calibration and large-scale networked measurement. A series of research accomplishments achieved by the team at the IMECAS are highlighted, including the development of six-degree-of-freedom laser trackers, the design of extended functional modules for laser trackers, and the construction of the industrialization system for laser trackers. The development trend of laser tracker technology is prospected. It is pointed out that various novel tracking and measurement methods and equipment derived from laser trackers will play a vital role in high-end equipment metrology and advanced manufacturing.

Abstract:Current multi-channel laser ranging technologies applied in accelerator alignment suffer from high equipment costs and complex system deployment. To solve these problems, this paper proposes a frequency-sweeping laser interferometric ranging technique adopting spherical collimators. A frequency sweeping laser interferometric ranging system integrated with HCN (H13C1?N) gas absorption cells, optical switches and spherical collimators was constructed to realize high-precision absolute distance measurement over a large range. A spherical collimator compatible with the target base of corner reflectors for laser trackers was designed, which reduces equipment costs while ensuring the required measurement accuracy. System performance tests were performed in an experimental environment simulating accelerator alignment. The results show that within the measurement range of 30 m, the ranging error of the proposed system is not more than 30 μm, fully satisfying the requirements of accelerator alignment. This system provides a high-precision and highly adaptable solution for accelerator alignment, and possesses great practical value in engineering applications.

Abstract:Existing calibration methods for ultra-micro-spot angle-resolved polarization scatterometers rely on rotating polarizers or liquid crystal retarders to calibrate the overall system parameters, resulting in complex operational procedures, difficulty in simultaneously decoupling multiple calibration parameters, and the introduction of additional error sources. To address these limitations, we propose an in-situ, stepwise calibration strategy for the system parameters of an ultra-micro-spot angle-resolved polarization scatterometer. Inspired by the principle of extinction ellipsometry, key system parameters — including the polarizer azimuth, ellipsometric parameters of the beam splitter in transmission and reflection, waveplate retardation and azimuth, ellipsometric parameters of the polarization beam splitter in transmission and reflection, and the orthogonally polarized transmittance of the objective lens — are sequentially calibrated with high precision. The proposed method was applied to calibrate a self-developed ultra-micro-spot angle-resolved polarization scatterometer, which was subsequently used to measure standard SiO₂ thin films and rectangular grating samples. The results demonstrate that, after in-situ calibration, the instrument achieved a film-thickness measurement repeatability of 0.1 nm, and the extracted grating morphology parameters exhibited excellent agreement with standard values, thereby verifying the effectiveness of the proposed calibration method.

Abstract:Conventional digital measurement methods suffer from low efficiency in measurement field construction and poor coordination among multiple devices, which cannot satisfy the high-precision and batch measurement and assembly requirements for large complex structures of new-generation aircraft. To address the above limitations, this paper investigates the multi-system collaborative precision measurement technology, establishes an uncertainty analytical model for large-scale measurement fields, and proposes an adaptive planning method. A multi-mode datum conversion standard artifact was developed to improve the construction accuracy of collaborative measurement fields. Meanwhile, a measurement planning technology based on lightweight models and task-device collaboration was put forward to realize the automatic sequence generation and simulation optimization for multi-station and multi-task measurement. On this basis, a multi-system collaborative precision measurement platform for the assembly of large complex structures was developed, which integrates multi-device control, measurement planning, and data management and analysis, achieving closed-loop control of the assembly measurement process covering "model-planning-measurement-analysis". Comparative experiments were conducted to verify the platform performance. The test results demonstrate that the proposed platform remarkably improves the measurement accuracy and efficiency, providing strong technical support for advancing the precise measurement and assembly technology of large complex structures in the aviation industry.

Abstract:The basic concept, waveform construction, and time-frequency mapping mechanism of the optical chirp chain (OCC) are introduced, and the fundamental principle by which OCC improves the acquisition efficiency of Brillouin spectra is elucidated. The operating principles of optical chirp chain Brillouin optical time-domain analysis (OCC-BOTDA) and optical chirp chain Brillouin optical time-domain reflectometry (OCC-BOTDR) are described. Research advances in OCC-BOTDA are reviewed in terms of single-shot ultrafast measurement, long-range and high-performance sensing, suppression of transient effects and spectral distortions, vector measurement, polarization diversity, and denoising enhancement. Progress in OCC-BOTDR is summarized with respect to single-ended online demodulation and sensing-performance improvement. The measurement range, spatial resolution, measurement time, and other performance parameters of different approaches are comparatively analyzed. Future directions for OCC-based fast distributed Brillouin sensing are discussed. Further advances are required in high-quality OCC generation, coherent detection, and digital signal processing. Moreover, OCC-based fast distributed Brillouin sensing can be integrated with other techniques to enable long-range, coordinated sensing of multiple physical parameters, while improving the engineering applicability and reliability of measurement systems to meet the demands of multiparameter monitoring in complex engineering environments.

Abstract:Currently, the heterogeneous node deployment schemes employed in sensor network applications for monitoring tasks suffer from suboptimal operational efficiency. To address this issue, this paper proposes the Optimal Deployment of Heterogeneous Node Positions in a Single-Sink Network (ODHNSS) algorithm. By jointly considering key performance indicators such as network coverage, the ratio of communication distance to communication radius, and the proportion of sleeping nodes, the algorithm establishes principled criteria for selecting optimal heterogeneous node locations, thereby enabling energy-aware optimization of heterogeneous node deployment in wireless sensor networks. Simulation experiments were conducted using MATLAB to comparatively evaluate the performance of ODHNSS against two state-of-the-art algorithms, Three-Tier Extended Energy-Efficient Clustering Hierarchy (TEEECH) and Optimal Deployment of Heterogeneous Nodes (ODHN). Results demonstrate that, relative to both benchmarks, ODHNSS significantly improves data transmission efficiency while simultaneously reducing overall network energy consumption, thus providing robust technical support for advancing wireless sensor monitoring network technologies.

Abstract:Aiming at the measurement errors caused by the resistance of high-temperature long wires and their temperature variations in long-distance strain testing of high-temperature structures for nuclear power applications, this paper proposes a strain correction method integrating strain gauge test data, measured strain gauge resistance and wire resistance values. The formation mechanism of strain measurement errors under long-wire transmission conditions is analyzed. By introducing resistance parameters of strain gauges and connecting wires, a unified correction model for measured strain is established to calibrate strain readings acquired at high temperatures. Based on the model, the thermal output curves and gauge factors are determined. High-temperature strain tests at 350 °C were performed to verify the effectiveness of the proposed method, which is further compared with the traditional three-wire method and half-bridge compensation method. The results demonstrate that the proposed method can simultaneously account for the coupled effects of wire resistance and its temperature drift, substantially reduce measurement errors, and improve the accuracy and stability of test results. This work provides critical technical support for enhancing the precision of high-temperature long-wire strain measurement in the nuclear power industry.

Abstract:To evaluate the aerodynamic performance and flow field quality of a full-scale test bench for a domestic high-bypass-ratio aero-engine, a computational fluid dynamics (CFD) simulation combined with measurement analysis was conducted. A three-dimensional model of the test bench, comprising an intake tower, silencing devices, a flow straightener, the aero-engine, an ejector duct, and an exhaust tower, was constructed using 3D modelling software. A refined mesh was generated, and the standard k-ε turbulence model with wall functions was employed to handle turbulence and near-wall flow. The flow governing equations were solved using the Semi-Implicit Method for Pressure Linked Equations (SIMPLE), and the distributions of velocity, pressure, and temperature fields, as well as natural convection characteristics, were analyzed. The results show that the ejection coefficient of the test bench reached 1.97, and the velocity non-uniformity at the cross-section 6 m upstream of the engine was 29.05%, which meets the relevant industry standard requirements. The flow straightener reduced the velocity non-uniformity by approximately 51.5%, significantly improving flow uniformity. The total pressure non-uniformity at the engine inlet was only 0.3%, indicating a low level of flow distortion. Under natural convection conditions, the wind speed inside the test bench remained below 2 m / s, and the impact of stack effect was limited. Overall, the test bench exhibits a reasonable aerodynamic design and excellent flow field quality, thus satisfying the ground test requirements for the domestic high-bypass-ratio aero-engine.

Abstract:To address the challenging measurement of oil-gas two-phase parameters in the return oil pipeline of an aeroengine lubrication system, a testing system for oil-gas two-phase flow of aeroengines based on electrical capacitance tomography has been developed. The cross-sectional phase fraction measurement is achieved using electrical capacitance tomography technology, and the flow pattern is regularized through a rectifier to enhance measurement accuracy, at the same time, the Venturi technology is utilized to achieve total flow measurement, ultimately leading to the measurement of gas-liquid two-phase flow. A calibration device for oil-gas two-phase measurement has been set up based on the field test bench for comparative testing of the measurement system. The results indicate that the maximum measurement error for liquid phase flow rate is 7.26 %FS, and the maximum measurement error for gas phase flow rate is 6.56 %FS under six experimental conditions. The research presented in this paper plays a crucial supporting role in the design of lubrication systems in the aeroengine field.

Abstract:To achieve accurate dielectric constant measurement of liquid and powder materials in the millimeter-wave band, this paper proposes a measurement method based on corrugated transmission lines. A dedicated test system was built using a customized polytetrafluoroethylene (PTFE) container and matched with vector network analysis technology for experimental testing. The Gated-Reflect-Line (GRL) calibration technique was adopted to mitigate measurement errors arising from multiple signal reflections and scattering between the container structure and the test samples. Following calibration, liquid or powder samples were loaded into the container, and the reflection S-parameters captured by a vector network analyzer were utilized to calculate the sample dielectric constant. Solid PTFE was tested as a standard sample to verify the feasibility and reliability of the established test system. Further experiments were conducted on quartz powder and dimethyl synthetic silicone oil within the frequency range of 75～110 GHz. The test results show that the maximum deviation of measured data from the average value is merely 5%, which verifies the superior accuracy of the proposed method. This study offers a crucial technical reference for millimeter-wave dielectric constant measurement of liquid and powder materials, supporting technical development in food processing, biomedicine and other related fields.

Abstract:To promote the layout of standard essential patents in China's aviation industry and enhance the integration of patents and standards in the high-end equipment manufacturing sector, this paper takes enterprises in the aviation industry chain as the research perspective to conduct patent retrieval and statistical analysis based on patent databases and industry standards repositories. The results show that patents within the aviation industry chain are insufficiently integrated with international standards, and their industrial adaptability remains weak，with room for improvement in quantity, track selection, mechanisms, operation and maintenance, and synergy. Based on the above analysis results and the domestic policy environment, application strategies and layout paths for standard essential patents are proposed. It is pointed out that efforts should focus on niche tracks with strong interoperability and that a multi-party collaborative whole-chain working mechanism should be established. This research can provide a reference for promoting the deep integration of patents and standards in the aviation industry and for high-end equipment manufacturing industry groups to carry out relevant domestic business.