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Ground subsidence caused by underground coalmining result in the formation of ponding water on the ground surface. Monitoring the surface water level is crucial for studying the hydrologic cycle in mining areas. In this paper, we propose a combined technique using Global Navigation Satellite System Real-Time Kinematic (GNSS RTK) and GNSS Interferometric Reflectometry (GNSS-IR) to estimate the surface water level in areas of ground subsidence caused by underground coal mining. GNSS RTK is used to measure the geodetic height of the GNSS antenna, which is then converted into the normal height using the local height anomaly model. GNSS-IR is employed to estimate the height from the water surface to the GNSS antenna (or, the reflector height). To enhance the accuracy of the reflector height estimation, a weighted average model has been developed. This model is based on the coefficient of determination of the signal fitted by the Lomb-Scargle spectrogram and can be utilized to combine the reflector height estimations derived from multiple GNSS system and band reflection signals. By subtracting the GNSS-IR reflector height from the GNSS RTK-based normal height, the proposed method-based surface water level estimation can be obtained. In an experimental campaign, a low-cost GNSS receiver was utilized for the collection of dual-frequency observations over a period of 60 days. The collected GNSS observations were used to test the method presented in this paper. The experimental campaign demonstrates a good agreement between the surface water level estimations derived from the method presented in this paper and the reference observations. [ABSTRACT FROM AUTHOR]

CoCrFeNi high-entropy alloy (HEA) exhibits excellent mechanical properties but relatively poor wear resistance. In particular, when the load reaches a certain level and the deformation mechanism of the CoCrFeNi HEA changes, the formation of shear bands leads to a significant increase in wear rate. Although numerous studies have been conducted on alloying strategies to improve the wear resistance of alloys, there is still limited research on the influence of deformation mechanism adjustment on wear resistance. Therefore, in order to fill this research gap, this study aims to use boron doping to regulate the deformation mechanism and successfully improve the wear resistance of CoCrFeNi HEA by 35 times. By observing the subsurface microstructure, the mechanism behind the significant improvement in wear resistance was further revealed. The results indicate that the reduction of shear bands and the formation of nanostructured mixed layers significantly improve wear resistance. The proposed strategy of boron doping to change the deformation mechanism and improve wear resistance is expected to provide new enlightenment for the development of wear-resistant HEAs. [ABSTRACT FROM AUTHOR]

The laser remelting technique was applied to the surface modification of the Al0.65CoCrFeNi high-entropy alloy (HEA) to further advance its mechanical potential. The microstructure of the remelted layer was refined from coarse dendritic to submicron-scale basket weave compared with the as-cast substrate, resulting in a 1.8-time increase in Vickers microhardness. The nanoindentation tests indicated that the nanohardness of the remelted layer was higher than that of each phase in the substrate. Meanwhile, the remelted layer retained considerable plasticity, as evidenced by its high Wp/Wt ratio (0.763) and strain hardening exponent (0.302). Additionally, adhesive wear prevailed on the substrate, while only abrasive wear features were observed on the remelted layer. Accordingly, the average friction coefficient and the wear rate of the remelted layer were minimized by 23% and 80%, respectively, compared with the substrate. Our findings explored an industrialized method to enhance the surface properties of the Al0.65CoCrFeNi HEA and also provided some helpful references for its laser additive manufacturing. [ABSTRACT FROM AUTHOR]

The refractory high-entropy alloys (RHEAs) have been the subject of considerable research in recent years. Since the Laves phase usually leads to a dramatic decrease in the malleability of RHEAs at ambient temperatures, it is critical to identifying the Laves-phase formation. Here, a facile and effective criterion is proposed to predict the phase stability based on the empirical parameters of reported RHEAs. The results indicate that the small atomic size difference is a sufficient condition for determining the stability of solid solution but not a necessary one. In general, the Laves-phase precipitates can be inhibited by decreasing the atomic-size difference, the enthalpy of mixing, and the valence electron concentration. These criteria can be easily adapted to design new RHEAs with the desired phase structure. [ABSTRACT FROM AUTHOR]

Summary: The present study was carried out to establish a dynamic microwave loading strategy for efficient production of high‐quality microwave freeze‐dried button mushroom based on non‐volatile taste components. The change behaviour of non‐volatile taste components of mushroom, including free amino acids and 5′‐nucleotides, was evaluated during microwave freeze‐drying with fixed microwave power. Then, the dynamic microwave loading strategy was established according to the change behaviour of the non‐volatile taste components. Drying and quality characteristics of mushroom were evaluated in terms of drying time, whiteness index, shrinkage ratio, rehydration ratio and vitamin C content. Results showed that high microwave power led to higher contents of free amino acids and 5′‐nucleotides at the initial stage of drying, but more degradation of these non‐volatile taste components was observed during the last period of drying. Moreover, it takes longer for 5′‐nucleotides to reach the highest content than total free amino acids. According to the evolution of non‐volatile taste components, a step‐down dynamic microwave power loading program (0–1.5 h: 4 W g−1; 1.5–4.5 h: 3 W g−1 and 4.5–10.5 h: 2 W g−1) was established to reduce the drying time, keeping a relatively high product quality. [ABSTRACT FROM AUTHOR]

Refractory high‐entropy alloys (RHEAs) with excellent high‐temperature performance are attractive for high‐temperature structural applications. However, many RHEAs suffer from high density and poor room temperature (RT) malleability. Herein, the effects of Ti and Nb contents on the phase equilibrium and mechanical properties of HfZrVTaMoWTixNby RHEAs are studied to achieve unique balanced properties in a wide temperature range. With the increase of Ti or Nb content, the Laves phase precipitation is suppressed and RT malleability is improved. Particularly, the HfZrVTaMoWTi2Nb2 RHEA without Laves precipitates exhibits a high yield strength of 1.7 GPa and a compressive strain of ∼30% at RT. Moreover, it retains a high systemic yield strength of 31 MPa cm3 g−1 at 1200 °C, which is nearly three times that of HfZrTaTiNb and nearly equal to that of MoWTaNb, suggesting its potential applicability at elevated temperatures. [ABSTRACT FROM AUTHOR]