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As power quality disturbances become increasingly complex, it is imperative that the speed and accuracy of the inspection robot at the converter station be improved. For this purpose, this study designs a power quality disturbance feature extraction method based on the fast‐adaptive S‐transform. This method preserves the main feature information and eliminates redundant calculations on the basis of adaptive transform. On this basis, a power quality disturbance identification model built on a multi label lightweight gradient elevator is constructed. In the experimental results, compared to the generalized S‐transform, adaptive S‐transform, and S‐transform, the total extraction time of the proposed method was reduced by 96.09%, 91.56%, and 91.22%, respectively. The average accuracy of extracting features for a single disturbance was 99.56%, while for complex disturbance, it was 98.24%, both of which outperformed the comparison algorithms. It is verified that the proposed method can improve the extraction accuracy of power quality disturbance signal. In the recognition of a single disturbance signal, the constructed model exhibited a high accuracy of over 99%. In recognizing composite disturbance signals, the model demonstrated high accuracy and strong stability. Its effectiveness has been confirmed through experiments. The paper aims to enhance the speed and accuracy of power quality disturbance recognition algorithms. This will assist inspection robots working in converter stations, and ensure stable and safe operation of the power grid. [ABSTRACT FROM AUTHOR]

A hybrid of halloysite nanotubes decorated with titanium dioxide nanoparticles (HNTs@TiO2) was synthesized by the sol–gel method and then mixed with ultra‐high molecular polyethylene (UHMWPE) by melt compounding to enhance its wear resistance properties. The incorporation of HNTs@TiO2 increased the crystallinity as well as the hardness of UHMWPE nanocomposites, which benefited less prone to plastic deformation during the friction process. In addition, the UHMWPE/HNTs@TiO2 maintained a high ductility character with a slight decrease in tensile strength compared to pure UHMWPE. With the addition of 3 wt% HNTs@TiO2, the UHMWPE nanocomposite achieved a remarkably low friction coefficient of 0.073 and a reduced wear rate of 6.67 × 10−6 mm3/N·m. These values represented a 32.4% decrease in friction coefficient and a 43.9% decrease in wear rate compared to pure UHMWPE. The improvement in wear resistance was due to the dislodged TiO2 and HNTs had good synergistic rolling effects at the counterface. Furthermore, the wear scan morphology observation revealed that the transferred HNTs@TiO2‐based materials could help to improve the quality of the tribofilms, which alleviated the abrasive wear from the metallic counterpart. This work offers a feasible way to enhance the wear resistance of UHMWPE nanocomposite without sacrificing the high ductility for expanding its engineering applications. Highlights: TiO2‐decorated halloysite nanotubes were synthesized by the sol–gel method.The addition of HNTs@TiO2 maintained the high ductility character of UHMWPE.The UHMWPE composite with 3 wt% HNTs@TiO2 had the best wear resistance. [ABSTRACT FROM AUTHOR]

Poly(3‐hydroxybutyrate‐4‐hydroxybutyrate) (P34HB) copolyester is a new type of biodegradable polymer material, but it cannot meet the market requirements because of its poor thermal stability. In this work, P34HB with a low degree of cross‐linking was successfully prepared by incorporating a small amount of a multiple epoxy chain extender, known as Joncryl ADR‐4380 (styrene‐methacrylic acid glycidyl ester copolymer), through reactive extrusion. The rheological properties, thermal stability, thermal behavior, and mechanical properties of the materials were investigated. Fourier transform infrared spectroscopy and gel content test showed that there was a significant chemical interaction between P34HB and ADR4380, and a cross‐linked structure was produced. Compared with pure P34HB, the samples after chain extension showed improved rheological properties, with increased viscosity and melt elasticity due to the formation of a gel network. Thermogravimetric analysis, dynamic time scanning experiment, and melt flow index (MFI) provided strong evidence for the enhanced of thermal stability of P34HB. The onset decomposition temperature of P34HB increased by 13.5°C, and its MFI decreased from 23.30 to around 5 at 170°C, and the complex viscosity remained relatively stable with time after modification. In terms of mechanical properties, the maximum elongation at break increased by 88.08% due to the improvement of toughness. [ABSTRACT FROM AUTHOR]

The inherent low dielectric constant of polyimide (PI) dielectrics restricts their applications to become a component of high energy density film capacitors. In this work, double core–shell structured barium titanate@magnesium oxide@polydopamine (BaTiO3@MgO@PDA) nanoparticles were synthesized successfully and utilized as high dielectric constant functional fillers for PIs, in which the insulating MgO layer meliorated dielectric constant difference between BaTiO3 and PI matrix, and the organic PDA layer improved the compatibility between the inorganic fillers and PI matrices. Then, a series of sandwich‐structured PI‐based hybrid films was prepared through a layer‐by‐layer solution casting method. The middle layer of pure PI with excellent insulating properties effectively suppressed charge injection. With the combination of sandwich structure and the BaTiO3@MgO@PDA nanoparticles, the PI hybrid film containing 15 wt% fillers in the outer layers achieved the maximum breakdown strength of 425.68 kV/mm and the maximum energy density of 5.132 J/cm3, which was 68.3% and 413% higher than those of pure PI film, respectively, meanwhile maintained a low dielectric loss value of 0.0083 at 1 kHz. The introduction of BaTiO3@MgO@PDA enhanced the interfacial polarization due to the high barrier energy between adjacent layers preventing the transfer of electrons and weakening the leakage current in the sandwich‐structured composite film. This work demonstrates that an appropriate combination of high dielectric hybrid fillers and multilayer structure can effectively increase the energy storage density of PI substrate for high‐temperature energy storage applications. Highlights: The double core–shell structured BaTiO3@MgO@PDA was synthesized successfully.The sandwich‐structured hybrid films were prepared by layer‐by‐layer method.The energy density of hybrid films reached a high value of 5.132 J/cm3. [ABSTRACT FROM AUTHOR]

The melting behavior and crystalline forms of isotactic polypropylene (iPP) samples crystallized under different conditions of pressure and temperature were investigated using differential scanning calorimeter (DSC) and wide-angle X-ray diffraction (WAXD), respectively. When treated with dynamic supercritical C[O.sub.2](Sc-C[O.sub.2]), iPP samples undergo the formation of (β-crystal that does not occur on the treatment with atmospheric pressure and static supercritical C[O.sub.2](Sc-C[O.sub.2]) pressure. In addition, the relative content of β-crystal has deep dependence on melt state and depressurization rate. Depressurization plays very critical role in the formation of β-crystal by means of imposing three-dimensional tensile field during cell growth. The tensile field induced a-row nuclei where the formation of β-crystal occurred. This finding will provide one new method to induce β-crystal in iPP parts., INTRODUCTION The crystalline forms of polypropylene (PP) have kept receiving considerable attention because they can affect many physical properties of PP at large degree. It is well known that three [...]