To control precisely and investigate maneuverability of an underwater vehicle in a nuclear power pool this article presents a study on the mathematical model and the thrust characteristics of a ducted propeller under the quasi-cavitation effect by a numerical method. Firstly, a mathematical model of a ducted propeller including the quasi-cavitation effect term which is often ignored, is established based on the thrust performance under different quasi-cavitation distances and the revolution speed by CFD. Then the pressure field near the suction and pressure surface of blades are analyzed, which reveals that the thrust increases with a decrease of the quasi-cavitation distance. Finally, the thrust performances under different conditions are experimentally measured in an open-water pool, which can verify the reliability of the mathematical model below the error of 10%. The results demonstrates that the presented method can be used to evaluate the dynamic mechanism of a propeller, and hold a potential to improve the control strategy.

Purpose: The purpose of this paper is to extend the usage of stroke gestures in manipulation tasks to make the interaction between human and robot more efficient. Design/methodology/approach: In this paper, a set of stroke gestures is designed for typical manipulation tasks. A gesture recognition and parameter extraction system is proposed to exploit the information in stroke gestures drawn by the users. Findings: The results show that the designed gesture recognition subsystem can reach a recognition accuracy of 99.00 per cent. The parameter extraction subsystem can successfully extract parameters needed for typical manipulation tasks with a success rate about 86.30 per cent. The system shows an acceptable performance in the experiments. Practical implications: Using stroke gesture in manipulation tasks can make the transmission of human intentions to the robots more efficient. The proposed gesture recognition subsystem is based on convolutional neural network which is robust to different input. The parameter extraction subsystem can extract the spatial information encoded in stroke gestures. Originality/value: The author designs stroke gestures for manipulation tasks which is an extension of the usage of stroke gestures. The proposed gesture recognition and parameter extraction system can make use of stroke gestures to get the type of the task and important parameters for the task simultaneously.

A dual-beam continuous-scanning spoof surface plasmon polariton (SSPP) leaky-wave antenna (LWA) with synergistic phase-reversal modulation and broadside radiation stabilization is proposed and experimentally validated. The antenna is built on a composite SSPP guiding unit composed of T-shaped resonator elements and semi-elliptical patches, which provides SSPP-type slow-wave guidance and supports spatial-harmonic radiation. Periodic phase reversal is introduced to excite the target −1st spatial harmonic and alleviate the open-stopband (OSB) effect caused by Bragg-reflection accumulation near broadside. Different from an isolated radiating patch, the semi-elliptical patch is incorporated as part of the composite SSPP unit and participates in the modal and dispersion behavior. Owing to its relatively weaker field confinement, it further facilitates residual broadside energy leakage and stabilizes the radiation response. As a result, broadside-stable dual-beam continuous scanning is achieved without an obvious gain dip around broadside. The fabricated prototype scans continuously from −90° to 48° over 5.61–7.84 GHz, with a scanning rate of 4.16°/% and an average gain of 10.6 dBi. The measured results agree well with simulations.

Remotely operated vehicle is a reliable tool in an emergency rescue and routing inspection of a reactor pool. In practice, a cable has been considered as an important part of a vehicle system (i.e. winch, vehicle, and cable) to evaluate and predict the mechanical characteristics, and this article presents a study on a dynamic mechanism modeling of a cable partially in water and air based on an omnidirectional motion, and a numerical simulation is employed. In this work, we programmed the model governed by a partial differential equation set, at the discrete time node which was transformed into an ordinary differential equation set regarded as an initial value problem. The dynamic mechanical characteristics of the lower endpoint (i.e. a connection point between vehicle and cable) and the upper endpoint (i.e. a connection point between cable and winch) were, respectively, quantified with acceleration and a compounded motion including a uniform and rolling motion. A dynamic-state mechanism test was carried out to verify an authenticity of the three-dimensional mechanical model and numerical solution in a circulating tank. The results demonstrated that the presented method was used to evaluate the dynamic mechanism, and held a potential to improve a vehicle design and control strategy.