Path Planning and Tracking Control for Parking via Soft Actor-Critic Under Non-Ideal Scenarios

Parking in a small parking lot within limited space poses a difficult task. It often leads to deviations between the final parking posture and the target posture. These deviations can lead to partial occupancy of adjacent parking lots, which poses a safety threat to vehicles parked in these parking lots. However, previous studies have not addressed this issue. In this paper, we aim to evaluate the impact of parking deviation of existing vehicles next to the target parking lot(PDEVNTPL) on the au...     

Observer-Based Adaptive Robust Precision Motion Control of a Multi-Joint Hydraulic Manipulator

Hydraulic manipulators are usually applied in heavy-load and harsh operation tasks. However, when faced with a complex operation, the traditional proportional-integral-derivative (PID) control may not meet requirements for high control performance. Model-based full-state-feedback control is an effective alternative, but the states of a hydraulic manipulator are not always available and reliable in practical applications, particularly the joint angular velocity measurement. Considering that it is not suitable to obtain the velocity signal directly from differentiating of position measurement, the low-pass filtering is commonly used, but it will definitely restrict the closed-loop bandwidth of the whole system. To avoid this problem and realize better control performance, this paper proposes a novel observer-based adaptive robust controller (obARC) for a multi-joint hydraulic manipulator subjected to both parametric uncertainties and the lack of accurate velocity measurement. Specifically, a nonlinear adaptive observer is first designed to handle the lack of velocity measurement with the consideration of parametric uncertainties. Then, the adaptive robust control is developed to compensate for the dynamic uncertainties, and the close-loop system robust stability is theoretically proved under the observation and control errors. Finally, comparative experiments are carried out to show that the designed controller can achieve a performance improvement over the traditional methods, specifically yielding better control accuracy owing to the closed-loop bandwidth breakthrough, which is limited by low-pass filtering in full-state-feedback control.

     

铁水中喷吹MoO3直接还原及合金化

本文讨论了在铁水中铝被直接还原的可能性;比较了喷吹法和团块法的处理效果;研究了钼对铁水的合金化作用。发现在1300-1550即1550℃温度范围内,在工业铁水中钼的直接还原和合金化可以同时完成。喷吹法比其它加入法能得到较好的效果。如这种新技术应用在工业上,可获得显著的经济效益。     

Pavement Cracks Coupled With Shadows: A New Shadow-Crack Dataset and A Shadow-Removal-Oriented Crack Detection Approach

Automatic pavement crack detection is a critical task for maintaining the pavement stability and driving safety. The task is challenging because the shadows on the pavement may have similar intensity with the crack, which interfere with the crack detection performance. Till to the present, there still lacks efficient algorithm models and training datasets to deal with the interference brought by the shadows. To fill in the gap, we made several contributions as follows. First, we proposed a new pavement shadow and crack dataset, which contains a variety of shadow and pavement pixel size combinations. It also covers all common cracks (linear cracks and network cracks), placing higher demands on crack detection methods. Second, we designed a two-step shadow-removal-oriented crack detection approach: SROCD, which improves the performance of the algorithm by first removing the shadow and then detecting it. In addition to shadows, the method can cope with other noise disturbances. Third, we explored the mechanism of how shadows affect crack detection. Based on this mechanism, we propose a data augmentation method based on the difference in brightness values, which can adapt to brightness changes caused by seasonal and weather changes. Finally, we introduced a residual feature augmentation algorithm to detect small cracks that can predict sudden disasters, and the algorithm improves the performance of the model overall. We compare our method with the state-of-the-art methods on existing pavement crack datasets and the shadow-crack dataset, and the experimental results demonstrate the superiority of our method.

     

〈铕(Ⅲ)/HNO3/N7402HTTA }〉及〈钆(Ⅲ)/HNO3/N7402HTTA }〉协同萃取的体系

本文报导了HTTA和N₇₄₀₂混合萃取剂萃取铕(Ⅲ)和钆(Ⅲ)的协同效应。分别测定了HTTA与N₇₄₀₂单独萃取,以及HTTA和N₇₄₀₂混合萃取剂协同萃取的最佳条件以及铕(Ⅲ)与钆(Ⅲ)的分离因数,这两个元素的协萃合物为离子缔合物,其稳定性呈现\     

感应电动机矢量变换控制的鲁棒性分析和参数自适应实现

采用矢量控制的感应电动机,其控制性能与它激直流电机类似,用这种控制方法,电机的转矩电流分量和磁通电流分量可实现解耦控制。本文讨论矢量控制系统的鲁棒性。针对前馈矢量控制系统中由于电机参数与速度检测小误差造成磁场定向错误,提出了一种新的自适应校正策略,该策略采用PRBS在线辨识技术,算法简单,不需要额外的传感器。最后给出了系统实现及实验结果。

     

酶解法制备柑橘皮渣膳食纤维的理化特性及抗氧化活性

分析6个不同香气型柑橘的果皮香气组分及关键香气物质成分,为柑橘果皮精油品质评价与发掘特殊香气柑橘精油提供依据。采用顶空-固相微萃取-气相色谱质谱联用法（HS-SPME-GCMS）分析柑橘果皮精油挥发性物质组成,结合相对气味活度值（relative odor activity value,ROAV）计算其关键香气物质构成。结果表明,从6个不同品种柑橘果皮精油中共鉴定出75种挥发性物质,其中单萜烯（73.82%~91.19%）含量最高,其次是醇类（4.32%~12.63%）和倍半萜烯（1.51%~10.20%）,它们共同作用形成柑橘果皮独特的香气。有23种化合物为6种柑橘果皮精油中共有,其含量达80.33%~94.59%。根据其化合物组成,可将6种柑橘果皮精油分为柠檬烯型、柠檬烯/γ-萜品烯型和柠檬烯/3-蒈烯型3个化学类型。ROAV法分析表明,芳樟醇是6种柑橘果皮精油风味贡献最大的物质。此外,衢州香橙、资阳香橙、青皮、南丰蜜橘、金秋砂糖橘和红美人果皮精油的关键香气物质种类存在明显不同,分别为8、14、11、8、13和18种,这些关键香气物质在柑橘果皮精油的独特香气形成中发挥重要作用。