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Abstract Thermal Barrier Coatings (TBCs) are functional coatings used to protect high-temperature components that are prone to early damage and premature failure under the influence of complex working conditions. This paper examines the crack propagation behaviour of 8% yttria-stabilized zirconia (8YSZ) EB-PVD TBCs under different oxidation conditions at 1100 °C. The morphology of interfacial cracks after oxidation was summarized and the evolution of thermally grown oxide (TGO) was quantified. Based on the evolution of TGO, the causes of crack propagation were analyzed. For the specimens after oxidation experiment, the interfacial crack propagation behaviour was observed and analyzed by SEM, and the reason of lateral crack propagation was explained from the perspective of interfacial fracture toughness. The reason for crack deflection is analyzed from the perspective of energy release rate. The equivalent thickness, normalized rumpling index and two-dimensional roughness index were calculated, then the TGO growth behaviour was comprehensively analyzed and related to the crack propagation.

To enhance the transplantation effectiveness of vegetables and promptly formulate subsequent work strategies, it is imperative to study the recognition approach for transplanted seedlings. In the natural and complex environment, factors like background and sunlight often hinder accurate target recognition. To overcome these challenges, this study explores a lightweight yet efficient algorithm for recognizing cabbage transplantation states in natural settings. Initially, FasterNet is integrated as the backbone network in the YOLOv5s model, aiming to expedite convergence speed and bolster feature extraction capabilities. Secondly, the introduction of the GAM attention mechanism enhances the algorithm’s focus on cabbage seedlings. EIoU loss is incorporated to improve both network convergence speed and localization precision. Lastly, the model incorporates deformable convolution DCNV3, which further optimizes model parameters and attains a superior balance between accuracy and speed. Upon testing the refined YOLOv5s target detection algorithm, improvements were evident. When compared to the original model, the mean average precision (mAP) rose by 3.5 percentage points, recall increased by 1.7 percentage points, and detection speed witnessed an impressive boost of 52 FPS. This enhanced algorithm not only reduces model complexity but also elevates network performance. The method is expected to streamline transplantation quality measurements, minimize time and labor inputs, and elevate field transplantation quality surveys’ automation levels.

Study region: The Taihu Lake is located at the downstream of the Yangtze River, China, which serves various functions such as regional flood control, drought resistance, and drinking water for many vital cities in China such as Shanghai, Hangzhou and Suzhou. Since 1950 s, Taihu Lake has experienced three stages of anthropogenic management. Due to these managements, the natural hydrologic properties of Taihu Lake are gradually disappearing, and the Taihu Lake tends to become an artificially controlled lake. Study focus: To understand how anthropogenic activities have impacted the hydrological regime of Taihu Lake at different stages, this study has analyzed daily average water level of Taihu Lake for 70 years and daily average precipitation data of the Taihu Lake Basin for 60 years. And finally it reveals the natural and anthropogenic effects on trend, amplitude, period and extreme water level of Taihu Lake. New hydrological insights for the region: The multi-year average water level of Taihu Lake witnesses an increment of 0.23 m, and the contribution from anthropogenic activities account for 34.78%. The maximum decrements of frequency of extreme high and low water level drops by 29.55% and 7.69% recently due to anthropogenic activities. The anthropogenic activities on the hydrological regime in Taihu Lake has become increasingly pronounced, and these hydrological changes are beneficial for basin flood control and water resources.

Iron impurities are believed to act as deep acceptors that can compensate for the n-type conductivity in as-grown Ga2O3, but several scientific issues, such as the site occupation of the Fe heteroatom and the complexes of Fe-doped β-Ga2O3 with native defects, are still lacking. In this paper, based on first-principle density functional theory calculations with the generalized gradient approximation approach, the controversy regarding the preferential Fe incorporation on the Ga site in the β-Ga2O3 crystal has been addressed, and our result demonstrates that Fe dopant is energetically favored on the octahedrally coordinated Ga site. The structural stabilities are confirmed by the formation energy calculations, the phonon dispersion relationships, and the strain-dependent analyses. The thermodynamic transition level Fe3+/Fe2+ is located at 0.52 eV below the conduction band minimum, which is consistent with Ingebrigtsen’s theoretical conclusion, but slightly smaller than some experimental values between 0.78 eV and 1.2 eV. In order to provide direct guidance for material synthesis and property design in Fe-doped β-Ga2O3, the defect formation energies, charge transitional levels, and optical properties of the defective complexes with different kinds of native defects are investigated. Our results show that VGa and Oi can be easily formed for the Fe-doped β-Ga2O3 crystals under O-rich conditions, where the +3 charge state FeGaGai and −2 charge state FeGaOi are energetically favorable when the Fermi level approaches the valence and conduction band edges, respectively. Optical absorption shows that the complexes of FeGaGai and FeGaVGa can significantly enhance the optical absorption in the visible-infrared region, while the energy-loss function in the β-Ga2O3 material is almost negligible after the extra introduction of various intrinsic defects.

Sound is an important aspect in working environment, and underground strong noise environment imposes a serious impact on operators' physical and mental health and easily leads to people's unsafe behaviors, thus giving rise to accidents. How to quantitatively study operators' behavioral reliability is a study hotspot. To mitigate the noise impact on operators and reduce the occurrence rate of accidents due to human factors, the relational models between noisy working environment and human physiological indexes were established first through a laboratory simulation, and then a reliability integral model was obtained using performance function and limit state equation. Second, the established reliability integral model was numerically simulated based on Monte Carlo numerical simulation method to obtain its numerical solution, and operators' behavioral reliability values under different sound pressure levels (SPLs) on fully-mechanized coal mining face were calculated. The results show that the behavioral reliability of fully-mechanized coal mining operators is high with low accident occurrence rate under noise SPL of 50-70 dB. Under 70-90 dB, their behavioral reliability is 0.7092 with potential accident risks. The behavioral reliability is low when SPL is 90-110 dB, under which accidents may easily take place. This study manifests that operators' behavioral reliability analysis under underground noise environment based on Monte Carlo method is of certain feasibility. The conclusions have a certain guiding significance for relieving human physical and mental harms incurred by noise, improving human behavioral reliability, reducing human errors and guaranteeing safety production.

Subsurface hydrodynamics underpin the eco-functions of salt marshes. Many studies have investigated these processes under various conditions. However, the impact of soil stratification (a low-permeability mud layer overlying a high-permeability sand layer) on the variable-density groundwater flow (particularly unstable flow) and solute transport in regularly tide-flooded marshes remains poorly understood. The present study numerically explored this question based on a 2D cross-creek section of salt marshes, by comparing cases with and without stratification. Results show that, the low-permeability mud layer delays the initiation of unstable flow and leads to smaller and denser salt fingers. Consequently, solute plume stays in the marsh soil for a longer time and spreads more widely than that in the homogeneous case. Also, soil stratigraphy extends the duration and shrinks the zone of solute discharge across the tidal creek. Sensitivity analysis was conducted based on three key controlling variables: hydraulic conductivity contrast between mud layer and sand layer (Kmud/Ksand), salinity contrast between surface water and groundwater (Csea/Cpore), and mud layer thickness (Dmud). The results demonstrate that the residence time of solute plume in a two-layered salt marsh is less sensitive to Csea/Cpore than to Kmud/Ksand and Dmud. Moreover, the commencement and duration of solute discharge are more sensitive to Kmud/Ksand and Dmud than to Csea/Cpore. While the location of solute discharge zone is highly sensitive to Dmud and slightly influenced by Kmud/Ksand and Csea/Cpore. Findings from this study would facilitate a deeper understanding of the eco-functions of salt marshes.

(1) Background: Blended learning (BL) models have attracted the attention of university teachers and students worldwide in recent years. However, systematic reviews related to the effectiveness of BL in university physical education are lacking. (2) Purpose: Therefore, this study aimed to evaluate the effects of BL in physical education among university students. (3) Methods: Searches were conducted in the following five databases: Web of Science, Scopus, PubMed, EBSCOhost (SPORTDiscus), and China National Knowledge Infrastructure (CNKI), and 18 articles met the inclusion criteria and were selected. The PEDro scale was used to assess the methodological quality of the selected studies and the quality of this study was fair (range 4–5). (4) Results: All reported sports included basketball (n = 6), badminton (n = 3), dance (n = 3), volleyball (n = 1), yoga (n = 1), aerobics (n = 1), Taiji (n = 1), swimming (n = 1), and tennis (n = 1). Seventeen studies described the effect of BL on students’ motor skills, and the results showed that BL had a greater effect on basic skills, but the improvement was not significant for combination techniques. There were three studies related to physical fitness. Studies have observed significant effects on lung capacity (n = 1), sit and reach (n = 1), pull-ups (n = 1), 1000 m (n = 3), and 800 m (n = 1). However, there was no significant difference in body weight (n = 1) or standing long jump (n = 1). In addition, two articles examined the impact of BL on sitting up, but the findings were the opposite. Six studies reported on exercise attitude and the results demonstrated that BL can significantly improve students’ learning attitude, target attitude, behavioral cognition, and emotional experience. However, the two articles produced different results in behavioral habits. Other results, such as satisfaction and interest in learning, were also popular topics regarding BL and were found to have improved significantly.

Based on the provincial panel data of China from 2001 to 2016, this study uses the social network analysis approach to empirically investigate the characteristics and driving factors of the spatial association network of China’s interprovincial renewable energy technology innovation. The findings are as following. 1) The spatial association of China’s interprovincial renewable energy technology innovation exhibits a typical network structure. Moreover, its network density, network hierarchy and network efficiency are 0.3696, 0.6667 and 0.7833 in 2001 and 0.4084, 0.4764 and 0.7044 in 2016, respectively, implying the spatial association network became more and more complex and the interprovincial association strengthened during the sample period. 2) This spatial association network presents a “core-edge” distribution pattern. The positions and roles of various provinces vary greatly in the spatial association network. Specifically, the developed coastal regions such as Shanghai, Beijing and Tianjin have a degree centrality, closeness centrality and betweenness centrality of above 75, 80 and 10, respectively, indicating that they always play a central role in the network. However, the northeastern regions and the relatively backward central and western regions such as Heilongjiang, Jilin, Xinjiang, Hainan and Hebei only have a degree centrality, closeness centrality and betweenness centrality of below 20, 55 and 0.1, respectively, indicating that they are at a relatively marginal position. 3) The geographical proximity and the expansion of the differences in economic development level and R&D inputs are conducive to the enhancement of the spatial association of China’s renewable energy technology innovation.

Watershed ecological compensation has been widely accepted as a system to promote the cooperation of various stakeholders to solve the problem of transboundary water pollution, but the existing research does not fully consider the impact of compensation fee paid by different governments on stakeholders’ decision-making. Therefore, this paper constructs a tripartite game model between upstream governments, downstream governments, and the central government by using evolutionary game theory and determines the influence of different factors on the decision-making process of each player through simulation. The results show the following: (1) the initial probability significantly affects the decision-making behavior of each player; (2) daily supervision of the central government and the reduction of the environmental protection cost can promote the implementation of watershed ecological compensation; (3) the fine to downstream governments makes the decisions of the central government and downstream governments change periodically; and (4) the increase of ecological compensation fee urges downstream governments to choose noncompensation, and compensation fee paid by the central government has a critical value.

A linear optimal regulator for uncertain system is designed through the application of the probability density evolution method to linear quadratic regulator controller. One important background of this work is bridge-vehicle/gun-projectile system. This type of optimal problem is currently transformed into a moving load problem. The developed optimal regulator can provide the law of probability densities of outputs varying with time. In order to make the advocated method reach an optimal performance, the beneficial weighting matrix pair ( Q, R ) is selected using a trade-off sense. The designed regulator is then applied to a coupled simply supported beam-moving mass system, choosing the mid-span deflection as an output response and considering stochastic system parameters. The numerical example shows that the robustness of the proposed optimal regulator cannot be overestimated in comparison with a deterministic linear quadratic regulator controller. Further, the proposed method can produce an efficient solution channel for modern optimal control theory, especially, when compared with different uncertain optimal control techniques.

Taking nickel-based single crystal superalloy DD6 as the research object, different degrees of creep damage were prefabricated by creep interruption tests, and then the creep damage was repaired by the restoration heat treatment system of solid solution heat treatment and two-stage aging heat treatment. The results show that with the creep time increasing, the alloy underwent microstructure evolution including γ′ phase coarsening, N-type rafting and de-rafting. After the restoration heat treatment, the coarse rafted γ′ phase of creep damaged specimens dissolved, precipitated, grew up, and became cubic again. Except for the specimens with creep interruption of 100 h, the γ′ phase can basically achieve the same arrangement as the γ′ phase of the original sample. The comparison of the secondary creep test shows that the steady-state creep stage of the test piece after the restoration heat treatment is relatively increased, and the total creep life can reach the same level as the primary creep life. The high temperature creep properties of the tested alloy are basically recovered, and the restoration heat treatment effect is good.

Landslide displacement monitoring plays a fundamental role in the study of landslide evolution mechanisms, forecasting, risk assessment, prevention, and control. To fill the deficiencies of traditional instrumentation for measuring landslide displacement distributed along lateral direction, a landslide displacement measurement method based on deformation-coupled pipeline trajectory measurement is proposed, and a pipeline trajectory inertial measurement instrument is developed. The developed instrument, primarily comprised of a single shaft gyro, two axis accelerometers, and an external roller encoder, is designed as an axial half strapdown-radial half platform structure combined with a mechanical gravity platform. This structure avoids the singularity of pitch angle and roll angle and can expediently calculate a pipeline trajectory with an Eulerian transformation when obtaining several basic physical variables, e.g., the axial linear velocity, pitch angle, roll angle, and azimuth angle. Additionally, the pipeline trajectory, measured at different times, possesses the ability to reflect the displacement evolution feature of landslides. The results of prototype simulation tests imply a single measurement accuracy of a 12 cm/100 m span and a singly periodic multiple (more than five times) measurement accuracy of a 3 cm/100 m span, which meets medium-precision displacement measurement requirements for a landslide. Additionally, the finished instrument has been successfully applied to the deformation monitoring of the Majiagou I# landslide, which further verifies its feasibility and offers a reference for similar landslides.

To harvest the energy of variable-speed wind, we proposed a dynamic multi-stable configuration composed of a piezoelectric beam and a rectangular plate. At low wind speeds, the system exhibits bi-stability, whereas, at high wind speeds, the system exhibits a dynamic tri-stability, which is beneficial for harvesting variable-speed wind energy. The theoretical analysis was carried out. For validation, the prototype was fabricated, and a piezoelectric material was bonded to the beam. The corresponding experiment was conducted, with the wind speed increasing from 1.5 to 7.5 m/s. The experiment results prove that the proposed harvester could generate a large output over the speed range. The dynamic stability is helpful to maintain snap-through motion for variable-speed wind. In particular, the snap-through motion could reach coherence resonance in a range of wind speed. Thus, the system could keep large output in the environment of variable-speed wind.

Hidden hazard risks of coal mine gas accidents significantly threaten the safety production of coal mine enterprises. Determining how these hidden hazard risks can be recognized and analyzing their action relations is a problem that the business and academic circles must urgently solve. To determine the action paths among hidden hazard risks of coal mine gas accidents and formulate scientific control measures, typical coal mine gas accidents during 2013–2023 in China were reviewed and analyzed based on the “human-equipment-environment-management” framework by combining the accident-causing theory. Twenty influencing factors were recognized and extracted using the grounded theory. Then, the degree centrality and betweenness centrality were determined for the influencing factors using methods derived from social network analysis. The hierarchy of influence of factors was determined, and the risk propagation mechanism in the system network was disclosed. Results reveal that coal safety management system and implementation, degree of safety standardization, investment in safety technology, and gas concentration have higher relative centrality than others. This finding reveals that these factors have a relatively higher influencing intensity on the risk system of coal mine gas accidents and have strong controls in the accident system. The key risk factors can easily intensify hidden hazard risks and cause the occurrence of accidents. The obtained conclusion provides a new decision-making idea for control coal mine gas risks. [ABSTRACT FROM AUTHOR]