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This paper proposes a voltage source converter (VSC) control strategy for the high voltage direct current (HVDC) transmission systems compensating the negative sequence and decaying DC (DDC) components. The mathematical model of the grid fault current is established firstly, and the DDC component is extracted using the property that the integral of the periodic signal is 0. Secondly, the fundamental wave component of the grid fault current signal is separated in the rotating frame system to obtain the compensation current command of VSC-HVDC. Finally, the performance of the proposed control strategy is compared with the conventional inverter control strategy when compensation the negative sequence and decaying DC (DDC) components by the experimental platform, and the experimental results show that the flexible HVDC transmission system with the proposed control strategy has the desired ability of compensating the negative sequence and DDC components simultaneously.

The Guangyuan kiln, located in the Sichuan Province, Southwest China during the Song Dynasty (960–1279 A.D.), is renowned for its high-temperature iron-series glazed wares, including pure black glazed ware, hare's fur glazed ware, glossy brown glazed ware, and matte brown glazed ware. To elucidate the raw materials, processing techniques, and coloration mechanisms of these wares, multiple analytical experiments were employed to investigate chemical composition, microstructure, and the phase of Fe-bearing minerals. We found that glossy brown glazed ware has the highest Fe2O3 content in the glaze (7.67 wt% on average), while pure black glazed ware exhibits the lowest (4.84 wt% on average). Higher Fe2O3 content leads to more iron for Fe-bearing mineral crystallization and larger ε-Fe2O3 precipitation. Based on microscopic observations, pure black glazed ware has numerous 100–250 nm crystalline grains, while hare's fur glaze ware features dendritic crystal flowers (200–400 nm), which exhibited liquid-liquid phase separation within the glaze, suggesting localized phase separation inducing iron oxide crystallization. Glossy brown glazed ware contains well-developed ε-Fe2O3 crystals (25 µm), and matte brown glazed ware, with the highest CaO and total flux, has acicular anorthite crystals alongside ε-Fe2O3 crystals. In summary, the decorative effect of four different types of iron-series glazed wares is determined by their chemical composition, phase composition, and microscopic structure. The findings offer valuable insights for the study of ancient iron-glazed ware. [ABSTRACT FROM AUTHOR]

The crystalline morphology and glaze color of Jian Kiln oil-spot glaze porcelain exhibit artistic beauty, making it one of the typical representatives of iron-based crystallized black porcelain from the Song Dynasty in China. This study sampled a series of specimens from key temperature points during simulation experiments, employing rapid air quenching to preserve the high-temperature state, capturing the formation process of oil-spot glaze crystals in Jian kiln ceramics. Key samples were subjected to microscopic structure and phase analysis using scanning electron microscopy (SEM), laser Raman spectroscopy (LRS), and X-ray photoelectron spectroscopy (XPS), revealing the formation mechanism of oil-spot glaze crystals in Jian kiln ceramics. The results indicate that the bubbles generated from the decomposition of iron oxide at high temperatures facilitate the migration and enrichment of iron-rich particles towards the glaze surface, laying a crucial material foundation for the subsequent crystallization process. The high-temperature reducing atmosphere accelerates the decomposition reaction of iron oxide, altering the concentration of Fe2+ in the glaze, the viscosity of the melt, and the surface tension, all of which are critical conditions that promote the formation of oil-spot glaze crystals. During the cooling phase, Fe3O4 nanocrystals oxidize into ε-Fe2O3 crystals, with external iron sources migrating inward to support ε-Fe2O3 crystal growth. This process gradually leads to the formation of micrometer-scale, leaf-shaped ε-Fe2O3 crystals that fully occupy the crystalline spots. The coloration of crystalline spots is closely tied to the size of the crystals. Thus, by adjusting the cooling regime, it is possible to create iron-based crystallization glazes with innovative color effects. Furthermore, this study offers significant insights for understanding the crystallization mechanisms of other ancient Chinese high-temperature iron-based crystallization glazes. [ABSTRACT FROM AUTHOR]

Jian kiln oil-spot glaze is one of the most typical iron crystal precipitation glazes in ancient China, and it is important to clarify the influence of iron oxide on precipitation glazes coloration and crystal precipitation, to provide a scientific basis and theoretical guidance for the development and innovation of iron crystal precipitation glazes with a variety of coloration effects. In this paper, XRD, Raman, SEM and EDS testing methods were used to investigate the microstructure of the precipitated crystals in glaze melt and the change rules of glaze coloration with different iron oxide content, and to reveal the mechanism of the glaze crystal structure on coloration. The results show that with the increase of iron oxide content, the glaze surface precipitates brownish-yellow, silver-blue, silver-white, silver-white and reddish-brown crystal spots, and the crystal spots are colored by chemical color and structural color coupling effect of crystals. The iron enrichment in the middle area of crystal spot is higher than that in edge area, and the phase change from ε-Fe2O3 to α-Fe2O3 takes place preferentially, forming different color effects. The middle area first precipitates 2 ~ 4 µm leaf-shaped ε-Fe2O3 crystals, with brownish yellow. With the increase of iron oxide content, the glaze layer precipitates with the glaze surface parallel to the directional arrangement of rod-shaped α-Fe2O3 crystals to form crystalline thin film, which produces a strong reflection of light, being silver-white. When the iron oxide continues to increase, the glaze precipitation of 10 ~ 20 µm dendritic α-Fe2O3 crystals penetrates the crystalline thin film, the structural color (silver) produced by the film is weakened, and the chemical color of α-Fe2O3 (reddish brown) is enhanced. The coupling is silver-white with reddish brown. The edge area first precipitates a large number of 30 ~ 50 nm grains, resulting in Rayleigh scattering as blue. With the increase of iron oxide content, the surface layer of rod-like crystals also forms a crystal film and the lower layer of film precipitates 100 ~ 200 nm plate nanocrystals to form amorphous photonic crystals. The coherent scattering is blue, and the reflected silver-white is coupled with silver blue. [ABSTRACT FROM AUTHOR]

The current three‐dimensional target detection algorithm for smart cars mainly uses three‐dimensional point cloud data collected by LiDAR. Effectively detect target objects in three‐dimensional space by applying various deep learning algorithms. However, under adverse weather conditions (such as rain, snow, fog, etc.), point cloud data collected by LiDAR may be distorted due to scattering and refraction. This affects the performance of the three‐dimensional target detection algorithm. This may lead to missed or incorrect detection of target objects, thereby affecting the driving safety and riding comfort of smart cars. This paper introduces two mainstream data processing strategies, namely data enhancement method in the model training stage and data preprocessing method in the model testing stage. Combine the two to improve model performance under the influence of adverse weather. [ABSTRACT FROM AUTHOR]