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Macroscale superlubricity on engineering steel surfaces offers a promising solution for minimizing friction and wear in engineering applications. However, achieving superlubricity typically requires a long running‐in period, which may result in significant wear for the friction pair. Herein, a new lubricant with superlubricating properties is rationally designed by using polyethylene glycol (PEG) and critic acid (CA) under complexing effect with a running‐in period of about 800 s. Importantly, the introduction of carbon quantum dots (CQDs) obtained from the pyrolysis of CA into PEG aqueous solution shortens the running‐in period for achieving macroscale superlubricity (µ ≈ 0.005) between steel/steel contact to 44 s. The corresponding wear rate (1.15 × 10−7 mm3 N−1 m−1) on the steel disk is reduced by 77% due to the shorter running‐in time. Furthermore, the surface analysis combined with the molecular dynamics simulations demonstrates that CQDs easily adsorb on the surface of the friction pair, forming a carbon film that reduces interaction energy between the lubricant molecules and the substrate. This work provides new insights into the lubrication mechanism of CQDs and contributes to the design of liquid superlubricants with short running‐in periods and low wear rates on engineering steel surfaces. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to investigate the effect of V doping on the microstructure, chemical stability, mechanical and vacuum tribological behavior of sputtered MoS2 coatings. Design/methodology/approach: The MoS2-V coatings are fabricated via tuning V target current by magnetron sputtering technique. The structural characteristic and elemental content of the coatings are measured by field emission scanning electron microscopy, X-ray diffractometer, electron probe X-ray micro-analyzer, Raman, X-ray photoelectron spectroscopy, high resolution transmission electron microscope and energy dispersive spectrometer. The hardness of the deposited coatings are tested by a nanoindentation technique. The vacuum tribological properties of MoS2-V coatings are studied by a ball-on-disc tribometer. Findings: Introducing V into the MoS2 coatings results in a more compact microstructure. The hardness of the coatings increases with the doping of V. The MoS2-V coating deposited at a current of 0.2 A obtains the lowest friction coefficient (0.043) under vacuum. As the amount of V doping increases, the wear rate of the coating decreases first and then increases, among which the coating deposited at a current of 0.5 A has the lowest wear rate of 2.2 × 10–6 mm3/N·m. Originality/value: This work elucidates the role of V doping on the lubrication mechanism of MoS2 coatings in a vacuum environment, and the MoS2-V coating is expected to be applied as a solid lubricant in space environment. [ABSTRACT FROM AUTHOR]

The multi-sensor scheduling problem of dual unmanned flight platforms has a complex coupling relationship, and how to reasonably match flight segments, sensors and targets is an intricate part of the problem. To solve the multi-sensor scheduling problem of dual unmanned flight platforms, a flight segment task allocation mechanism was proposed in this study, which assigned tasks through the position relationship between the flight segment and the target. This mechanism could effectively split the tasks and solve the task coupling problem of the two platforms. Pre-processing targets and sensors were carried out to identify scarce sensor resources and independent targets in advance to guide subsequent scheduling matching. Then, sensor-target matching was carried out to plan the scheduling of sensors based on the task revenue. The scheduling of conflicting segments was adjusted according to the availability of sensor resources. Finally, task migration was carried out for targets that still need to complete their assigned tasks. The available free sensors in the corresponding flight segments were matched according to the target task remaining to improve the task revenue. In order to verify the effectiveness of the proposed algorithm in this study, existing algorithms were compared through simulation experiments on 10 test problems. The experimental results showed that this algorithm outperformed existing algorithms in task revenue and stability with a significant reduction in running time. [ABSTRACT FROM AUTHOR]

The turnover rate of social workers is extremely high and the predictive roles of professional identity and job burnout on turnover intention have not been explored in China. The study examined the relationship between professional identity and turnover intention, mediated by job burnout and moderated by a social work degree, amongst social workers in China. Based on a sample of 829 participants and the structural equation model method, the findings confirmed that professional identity per se was not related to turnover intention, and a mediating role of job burnout and a moderating role of a social work degree were identified. [ABSTRACT FROM AUTHOR]