This study investigates the formation of electrical fluting erosion on bearing surfaces using a lubricated ball-on-disc tribometer. The “washboarding effect” is firstly proposed to account for fluting evolution during electrical erosion. Results show that elevated voltage extends the discharge region beyond the Hertzian contact area. Thicker oil films, resulting from higher velocity or viscosity, increase the critical breakdown voltage and decrease the fluting spacing. Additionally, mechanical-electrical coupling under slide-roll conditions significantly exacerbates surface degradation. Fluting is observed to evolve from initial frosting damage. Analogous to the “washboard” phenomenon on the unpaved roads, it is thought the initial ridge/flute morphology is irreversibly recorded and progressively amplified under follow-up rolling, forming fluting erosion with alternating “bright” and “dark” areas.
Besides improving environmental conditions, large scale ecological restoration initiatives carry implications for households' livelihoods. Therefore, evaluating whether restoration policies can align ecological objectives with income growth is important for promoting environmentally sustainable development. We study whether China's Integrated Protection and Restoration Project of Mountains, Rivers, Forests, Farmlands, Lakes, Grasslands, and Deserts, commonly known as the Shan-Shui Initiative, has helped promote rural income growth as well as the channels through which income effects operate. Using a panel of 1700 counties from 21 provinces, we estimate policy effects for the period 2016–2022 with a synthetic control approach that uses machine learning to construct counterfactual income paths for treated counties. Our results show that the initiative has increased rural incomes with gains growing over time. Estimated effects differ by pilot batch, with incomes rising by about 5% and 1.9% for the first two project cohorts implemented in 2016 and 2017, respectively, but decreasing by 0.9% for the final batch in 2018. After adjusting for potential anticipation effects, the estimated effect for the 2017 cohort increases to 3.7%. We demonstrate that ecological restoration promotes rural incomes via improvements in ecosystem services, infrastructure, and tourism development. Income effects are generally larger in more economically developed and less ecologically fragile areas, while differences across dominant project types are comparatively modest. The results provide insights into potential policies for aligning environmental protection objectives with rural development.
Icing of engineering equipment is widely occurring in cold and humid environments, and ice thickness is a critical parameter for determining when to activate or deactivate de-icing operations. Thermal-based ice detection methods offer numerous advantages, such as low cost and compact size. However, their application is limited by their inability to measure ice thickness. To fill this technical gap, a novel thermal pulse ice thickness detection method is proposed in this study. Through experimental analysis of the transient temperature response of uniform ice layers of varying thicknesses under thermal pulses of varying power and duration, and by incorporating changes in parameters such as ambient temperature and airflow velocity, a mathematical model relating thermal pulses to ice thickness was established, and the mapping relationship between thermal response characteristics and ice thickness was determined. The results show that this method enables high-precision detection of uniform ice thickness, with an average error of 10.11% for ice thicknesses ranging from 0 to 14 mm at −10 °C. By optimizing the model based on the coupling of the peak measured temperature and the time of its occurrence, the average error can be further reduced to 7.31% for ice thicknesses ranging from 0 to 7 mm. The results of this study provide valuable references and insights for enriching dynamic icing parameters detection methods, developing low-cost, high-precision, and highly efficient anti-icing and de-icing technologies, and enhancing the adaptability of engineering equipment to cold and humid environments.
Graphite suffers from temperature-dependent oxidative degradation and unstable friction across wide thermal ranges. Conventional single-system modifications exhibit restricted versatility and inherent limitations under complex operating conditions with temperature fluctuations. To address this issue, an organic-inorganic composite impregnation system based on KH550 and aluminum dihydrogen phosphate (AP) was developed for graphite modification. The effects of composition ratio on the thermal stability, mechanical properties, and tribological behavior of impregnated graphite were systematically investigated at room temperature, 400 degrees C, and 650 degrees C. The results reveal a temperature-dependent synergistic lubrication behavior. At 400 degrees C, the KH550-rich sample exhibits the best wear resistance, achieving a 91.7% reduction in wear rate compared with pristine graphite. At 650 degrees C, the AP-rich sample demonstrates superior high-temperature tribological performance, resulting in a 79% reduction in wear rate. Meanwhile, the sample with balanced KH550 and AP contents maintains stable friction and wear behavior over a wide temperature range. These findings demonstrate that organic-inorganic composite modification provides an effective strategy for tailoring the high-temperature tribological performance of graphite and offers potential for wear-resistant components in aero-engine applications.
Abstract We investigate the properties of strange quark matter (SQM) at zero temperature within the confined-isospin-density-dependent-mass (CIDDM) model by incorporating the vector interactions. The equation of state (EOS), equivalent quark mass, isospin asymmetry, and polytropic index of SQM are analyzed. We find that including the vector interactions can significantly stiffen the EOS, thereby enhancing the maximum mass of quark stars (QSs). Considering the vector interactions within CIDDM model, the mass-radius relation of QSs can describe the recent discovered massive compact object as QSs and can satisfy the observational constraint regions of PSR J0740+6620, 4U 1702−429, PSR J0030−0451, PSR J0437−4715, PSR J0614−3329, and HESS J1731−347. In particular, our results indicate that more massive QSs in this framework exhibit smaller polytropic index, lower central baryon densities, and lower central energy and central pressure of QSs.
