Subgrade deformation under load is accumulated from the local compressive strain of each layer. Solely relying on the overall settlement monitoring at the top surface makes it difficult to reveal the internal strain distribution and the evolutionary characteristics of early damage. Therefore, acquiring the local compressive strain field along the depth direction is of great engineering significance for subgrade condition assessment and safety early warning. In this paper, a vertically installed FBG sensor (VI-FBG) with GFRP packaging suitable for layered strain measurement of subgrade is developed. The effectiveness of the sensor is verified by direct compression tests and compressive strain tests with the sensor embedded in concrete. Furthermore, the sensor was buried in the subgrade of a high-speed railway to carry out strain monitoring. The test results show that the sensor has favorable sensing performance, with a strain sensitivity of 1.2 pm/με and a temperature sensitivity of 16.84 pm/°C. The measured compressive strain of concrete is in good agreement with the theoretical value, and the relative error is less than 8%. The field monitoring data can truly reflect the vertical compressive strain during subgrade filling. The measured time-history curve exhibits good consistency with the displacement time-history curve obtained by the adjacent FBG settlement sensor. This study verifies that the sensor is applicable to the monitoring of local vertical compressive deformation of subgrade, and its GFRP encapsulation endows it with good engineering applicability.

The Zhuxihe River has faced significant water quality challenges in recent years. Although control measures have been implemented, the pollution levels remain concerning. This paper aims to investigate the spatio-temporal variations in the water quality of the Zhuxihe River through field sampling, chemical testing, and synthetic evaluation. We collected 52 water samples in both dry and wet seasons along the main river and its tributaries. The evaluation, which utilized the integrated SFE-FCE method, identified MnO₄²⁻, NH₃-N, TP, and TFe as the primary pollutants. In the dry season, MnO₄²⁻ concentrations ranged from 1.6 mg/L to 19.8 mg/L, NH₃-N ranged from 0.12 mg/L to 2.04 mg/L, and TP concentrations varied from 0.1 mg/L to 5.61 mg/L. In the wet season, MnO₄²⁻ concentrations ranged from 4.9 mg/L to 13.9 mg/L, NH₃-N from 0.27 mg/L to 1.73 mg/L, and TP from 0.07 mg/L to 1.31 mg/L. The results indicate the concentrations of MnO₄²⁻ are higher in the wet season, and TP and NH₃-N show seasonal fluctuations. Spatially, the downstream section of the main river faces the highest pollution levels. This study provides insights into the pollution dynamics of the Zhuxihe River, offering a scientific foundation for future research and water quality management strategies.

To resolve the discrepancy between the measured strain and the actual surface strain of wind turbine blades when using rubber-encapsulated fiber Bragg grating (FBG) sensors for strain monitoring, this study establishes a surface-bonded strain transfer model for such sensors. The total strain transfer efficiency of the sensor is decomposed into two components: the strain transfer efficiency from the rubber substrate to the FBG core (encapsulated grating strain transfer efficiency) and that from the wind turbine blade to the rubber substrate (strain transfer efficiency between the rubber substrate and the blade). Based on the theory of mechanics of materials, the strain transfer equation is derived, and the key factors influencing strain transfer efficiency—FBG bonding length and rubber substrate thickness—are analyzed via the control variable method. Three ethylene propylene diene monomer (EPDM)-encapsulated FBG sensors with rubber substrate thicknesses of 3 mm, 4 mm, and 6 mm were fabricated. Tensile strain transfer tests were conducted using fiber-reinforced plastic (FRP) strips to simulate the material properties of wind turbine blades, so as to validate the effectiveness of the proposed model. The experimental results demonstrate that the strain transfer efficiency of the sensor increases with the extension of FBG bonding length and decreases with the increase in rubber substrate thickness, with 4 mm determined as the optimal substrate thickness for EPDM-encapsulated FBG sensors. On the basis of the aforementioned findings, an EPDM-encapsulated FBG strain rosette sensor was developed, which can effectively measure the complex stress of a wind turbine blade model. This study provides a theoretical foundation for the structural design and engineering application of rubber-encapsulated FBG sensors in the strain monitoring of wind turbine blades.

The effect of low-molecular-weight dissolved organic matter (LDOM) on antimony enrichment in groundwater remains unclear. In this study, the spectroscopic and molecular characteristics of high- and low-Sb groundwater are compared using optical spectrophotometry, ultrafiltration, and Fourier transform ion cyclotron resonance mass spectrometry. The results demonstrated that although the mean DOM concentration in LDOM groundwater (3.98 mg/L) accounted for only 69.22% of the mean DOM concentration, the proportion of Sb(V) within the total Sb varied between 80.29% and 99.56%. LDOM was characterized by higher biological and fluorescence index values, a greater H/C ratio, and reduced double-bond equivalent values compared with high-molecular-weight dissolved organic matter. High abundances of LDOM can enhance the primary enrichment of Sb(V) within the total Sb concentration via competitive adsorption and, as energy and electron acceptors for microbial communities facilitate Sb(III), oxidation within groundwater systems. This study provides new perspectives on understanding how DOM influences the migration and speciation transformation of Sb in groundwater environments.

Wind turbine blades serve as the core components of wind energy conversion systems, and their safe and stable operation is pivotal to the operational efficiency and reliability of wind farms. However, prolonged operation in harsh environmental conditions such as strong winds, heavy rainfall, ultraviolet radiation, and temperature fluctuations renders wind turbine blades susceptible to fatigue damage and structural failure. Aiming at the drawbacks of traditional electromagnetic sensors, including their vulnerability to lightning strikes and poor corrosion resistance, as well as the elastic modulus mismatch between existing fiber Bragg grating (FBG)-encapsulated sensors and wind turbine blade structures, this study selects the ethylene–propylene–diene monomer (EPDM) as the encapsulation material to develop EPDM-FBG strain sensors. The effectiveness of the proposed sensor in blade strain monitoring is ultimately verified via static load model tests on small-scale wind turbine blades. Test results demonstrate that the EPDM-FBG strain sensor exhibits excellent static strain sensing performance, with its test results being highly consistent with those of bare FBG sensors and a relative error of less than 5%, which can fully meet the practical requirements of static strain monitoring for wind turbine blades. This research provides a novel and reliable monitoring method for the health monitoring of wind turbine blades.