A polar crane is a large-scale special lifting equipment operated in a nuclear power plant. To address the precise locating control problem of a polar crane with the center of gravity shifting, with cross-coupling, and with external disturbance, an effective control scheme is proposed in this paper. Firstly, a nonholonomic constraint dynamic model of the polar crane is established according to the Lagrange–Rouse equation. Then, an expansion state observer (ESO) of the active disturbance rejection control (ADRC) method is applied to estimate and compensate the cross-coupling disturbance in real-time. To improve the robustness and convergence speed of the control system, the nonsingular terminal sliding mode (NTSM) control method is incorporated with ADRC and the stability of the controller is proven by the Lyapunov function approach. Furthermore, to solve the problem of redundant actuation and to reduce trajectory deviation of the bridge truck, the contact forces of the horizontal guide device are introduced into the quadratic programming (QP) optimization algorithm. Finally, the effectiveness and superiority of the proposed control scheme are illustrated by simulation results.

Surface micro-discharge (SMD) has received growing interest for its great prospect in various emerging applications spanning the fields of biomedicine, manufacturing, and agriculture. Discharge properties and the nature of the chemical species are heavily dependent on the electrode configuration. However, insight into the effect of electrode configuration on SMD remains scarce. This paper reports on the effect of the geometry of the powered planar electrode on the dynamic evolution of plasma in a helium SMD array at atmospheric pressure. The observed symmetric and asymmetric luminous patterns correspond to odd and even numbered current pulses in negative half-cycle, respectively. When the powered electrode is not covering the full area of the mesh unit of the grounded electrode, the luminous pattern dominated by the negative pattern consists of three parts: the distinct luminous channel, the flabelliform luminous area, and the discontinuous cambered channels under the incomplete powered electrode condition. The distinct luminous channel is ascribed to the propagation of the bullet-like plasma volume originated at the middle part of the mesh side before merging with other plasmas. The merging plasma forms a cambered front and continuous to propagate, leading to the formation of a flabelliform area. The discontinuous cambered channels result from the propagation of bullets ignited at the mesh corners, especially the slide of luminous area with maximum emission intensity along the streamer. Moreover, the mesh element without a powered electrode can also initiate breakdown due to the sufficiently high voltage and the propagation of surface charges, suggesting that the grounded mesh electrode should be extended to avoid redundant discharges.

The research of the chemically active species of cold atmospheric pressure plasmas is a essential step for a more in-depth comprehending the effects of its interaction with target. In this paper, the temporal and spatial evolution of key species O3, NO2and NO3produced by surface micro-discharge in air were investigated. UV-VIS optical absorption spectroscopy at 254 nm, 400 nm and 662 nm were used to measure the concentrations of O3, NO2 and NO3, respectively. The results show that the temporal evolution of O3, NO2 and NO3 are revealed a significant correlation with the surface power density. The phenomenon of O3 and NO3 quenching occur once the surface power density overcomes a critical value of 0.15 W/cm2. An O3-enriched atmosphere (peak concentration around 3000 ppm) is formed when the surface power density below the critical value, and a NO2-enriched atmosphere (maximum NO2 density around 600 ppm) is formed at higher surface power density. In addition, the concentration distribution of O3, NO2and NO3in the chamber ranging from 10 - 100 mm of the downstream of the mesh electrode tends to be uniform. Finally, a zero-dimensional model of the afterglow chemistry validated using the experimental measurements is developed to determined important reactions affecting O3, NO2 and NO3 respectively, and obtain insight into the evolutionary behavior of the considered reactive species.