Search

Unmanned aerial systems (UASs) find diverse applications across military, civilian, and commercial sectors, including military reconnaissance, aerial photography, environmental monitoring, precision agriculture, logistics, and rescue operations, offering efficient, safe, and cost-effective solutions to various industries. To ensure the stable and reliable operation of UASs, fault diagnosis is essential, which can enhance safety, and minimize potential risks and losses. However, most existing fault diagnosis methods rely on a single physical quantity as the primary information source or solely consider fault data at a single moment, leading to challenges of low diagnostic accuracy and limited reliability. Aimed at this problem, this paper presents a fault diagnosis method based on time–space domain weighted information fusion for UASs. First, the Gaussian fault model is constructed for the data with different fault features in the space domain. Next, the weighted coefficient method is used to generate the basic probability assignment (BPA) by matching the fault data with the Gaussian fault model. Then, the Dempster's combination rule, which enables the Dempster–Shafer (D-S) evidence theory, is adopted to fuse the generated BPAs. Based on this, the pignistic probability transformation is performed to determine the fault type. Finally, numerical results demonstrate the effectiveness of the proposed fault diagnosis method in accurately identifying the fault types of UASs. [ABSTRACT FROM AUTHOR]

This study proposed a new magnetic abrasive finishing (MAF) method, in which a 6-axis robot with a magnetic machining tool was used to polish the inner surfaces of curved tubes. We have also developed a magnetic machining tool jig, which can be fixed at the front of the 6-axis robot, rotating freely and suitable for polishing the inner surfaces of curved tubes. In this study, we focused on investigating the machining parameters in the initial machining stage and precision finishing stage. Based on the characteristics of machining parameters, a multi-stage MAF process was conducted to obtain an inner surface with high quality and high efficiency. The experimental results showed that both the roughness Ra and Rz of inner surface in the initial machining stage significantly decreased with the increase in the mixed magnetic abrasives, to as low as less than 20 nm Ra in the precision finishing stage when the machining parameters were appropriately adjusted. In addition, the roughness Ra of inner surface could be further reduced to less than 10 nm Ra in the multi-stage MAF process. Finally, the magnetic flux density cloud map and the magnetic field line distribution map were analyzed in Ansys Maxwell. [ABSTRACT FROM AUTHOR]

Microplastics that are ubiquitous in environmental media are considered to be effective carriers for the migration and transformation of organic pollutants. Exploring the interaction between microplastics and organic pollutants has become a research hotspot in the environmental field. In this paper, dimethyl phthalate (DMP) and diethyl phthalate (DEP) were selected as the target pollutants, and the adsorption behavior and mechanism of two typical microplastics polyethylene (PE) and polyvinyl chloride (PVC) to DMP and DEP were mainly studied. The results show that the two kinds of microplastics have adsorption capacity for DMP and DEP, and the adsorption capacity of PE is greater than that of PVC, which may be related to the type of microplastics and the specific surface area and porosity. The adsorption capacity of the same microplastic to DEP is greater than that of DMP, which is mainly related to the physical and chemical properties of pollutants. The pseudosecond-order model can well describe the adsorption kinetic process of two microplastics to DMP and DEP, both intraparticle and film diffusion could dominate the adsorption. The adsorption isotherm can be well fitted by the Linear model, the Langmuir model and the Freundlich model. The adsorption process is distributed by hydrophobicity. The role is dominant, and there may be a micropore filling effect. [ABSTRACT FROM AUTHOR]