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Latest articles for Measurement Science and Technology

IOPscience

  • Magnetic-flux-based plumb line coordinometer for horizontal displacement monitoring of dam
    Monitoring the horizontal displacement of plumb lines is essential for guaranteeing the safety of dams. A magnetic-flux-based plumb line coordinometer, which is immune to environmental changes in dust concentration and humidity, is proposed. Firstly, the theoretical relationship between the displacement and the measured magnetic field is derived from the magnetic circuit theory, and the dimensions of the sensor have been optimized. Secondly, the effect of plumb line eccentricity on the displacement measurement is studied and a structure with ferromagnetic guide is proposed to reduce this effect. Finally, a plumb line coordinometer device is fabricated to measure displacements in two orthogonal directions, and a decoupling algorithm is proposed to obtain displacements in two directions. Based on the experimental results, the coordinometer can measure displacement in two orthogonal directions with a maximum error of 0.09 mm within the 60 mm measurement range. The developed plumb line coordinometer has been installed in a hydroelectric power plant for on-site testing, and the displacement measurement results are in good accordance with the optical method and artificial observation.

  • Bearing fault diagnosis domain generalization network based on multi-scale feature alignment
    Domain generalization in fault diagnosis (FD) faces significant challenges, primarily due to its inability to fully leverage multi-scale feature information. This study proposes the multi-scale feature alignment-based domain generalization network for bearing FD, which overcomes the limited diagnostic performance of previous networks that focus solely on single-scale feature information. First, the generalized s-transform is employed to convert one-dimensional vibration signals into two-dimensional time-frequency representations. Next, a multi-scale feature extractor is designed by integrating the coordinate attention mechanism, the gate recurrent unit module, and the transformer encoder module, enhancing the model’s capacity to extract features at multiple scales. Furthermore, the training process is enhanced by combining the maximum mean discrepancy and correlation alignment (Coral) loss functions. Finally, adversarial training strategies are employed to boost the diagnostic accuracy of the discriminator, thereby strengthening the model’s adversarial diagnostic capabilities. The proposed method was experimentally validated using a self-constructed bearing fault dataset and a publicly available bearing fault dataset from Jiangnan University (JNU). The results indicate that, on the self-constructed dataset, the proposed method achieves an accuracy of 98.54% in the multi-source domain diagnosis task, marking a 6.74% improvement over the inadequate source domain task. Additionally, for the insufficient source domain diagnosis task on the JNU dataset, an average accuracy of 92.52% was attained. These results thoroughly demonstrate the reliability and effectiveness of the proposed method.

  • Development and validation of an automatic filter-replacement coal dust concentration detector based on light extinction
    Particulate matter in the workplace has a significant impact on environmental pollution and the health of workers. Accurate real-time monitoring of particulate matter concentration is essential for preventing and controlling environmental pollution. This study presents the development and performance evaluation of a coal dust mass concentration monitoring device based on the light extinction principle, integrated with an automatic filter replacement system. A detection model was established to convert light extinction signals into mass concentration values by applying the Lambert–Beer law combined with linear regression analysis. To mitigate the contamination of optical components caused by dust particles, an automatic filter tape mechanism was designed, inspired by the BAM-1020 β-ray particulate monitor, enabling long-term continuous monitoring. Through experimental comparisons, an infrared LED light source with a 30° emission angle and an SPS0606 silicon photodiode were selected as the optimal optical detection components. Additionally, using experimental data from three representative coal dust types—lignite, bituminous coal, and anthracite—a light extinction-based detection model was constructed, demonstrating strong stability and adaptability across different coal types and particle sizes. Finally, a comparative experiment was conducted between the prototype and a commercial PMS1600 light scattering dust sensor, with filter weighing method serving as the reference standard. Results show that the prototype achieved a relative error within ±15% under low concentration conditions (<25 mg m−3) and within ±10% under high concentration conditions (>25 mg m−3), meeting the accuracy requirements for practical applications.

  • Automatic projector defocus measurement method with large depth of field for fringe projection system
    The optimal defocus method is proved to be helpful to improve the accuracy of fringe projection measurement system. Using this characteristic, this paper proposes an automatic projector defocus method by using a self-designed control module to adjust the projector lens precisely. By applying automatic defocus to large depth of field measurements, the optimal defocus level at any position within the measurement range is determined. First, the gray histogram wave peak detection method is used to divide the object’s point cloud into multiple parts, and the optimal defocus measurement is performed to obtain multiple groups of point clouds. Then the linear interpolation method is used to solve the error of each point in the point cloud. Finally, the corresponding points are fused to get a set of point clouds with higher precision. The feasibility and effectiveness of the method are validated by experiments, which demonstrate an improved measurement accuracy of about 16% to the traditional method without defocusing.

  • Large area high-speed atomic force microscopy with arbitrary scan path playback
    High-speed (up to 3 mm s−1) atomic force microscope imaging over large ranges (up to 100  ) is demonstrated using arbitrary non-raster scan paths. This scanning has been achieved by using a new approach to motion control with preprogrammed coordinates applied to a Queensgate XY-100D stage. This position-velocity-time type control gives smoother motion at high-speeds (HSs) compared to a real time control approach. Additionally a larger area of 0.5 mm  ×  0.7 mm is imaged by moving the HS stage on a coarse positioner and stitching data.