No abstract

Real-time status monitoring is an important prerequisite for coral reef ecological protection. Existing equipment does not provide an ocean observation platform with adequate mobility and efficiency. This paper describes the design considerations of a proposed autonomous underwater helicopter (AUH) dedicated for ecological observation of coral reefs, including the system architecture, electronic devices, sensors and actuators, and explains the path control algorithm and controller to follow a specific path for ocean exploration. The structure and dynamic model of the AUH are first introduced, and then the corresponding simplification is made for motion analysis. Furthermore, computational fluid dynamics (CFD) simulation is carried out to evaluate the dynamic performance of the AUH. Fuzzy-PID control algorithm is utilized to achieve a good antidisturbance effect. In order to validate the performance of the proposed underwater vehicle, a field test was performed, and results confirmed the feasibility of the proposed prototype.

Direct water injection provides feasible solution for combustion optimization and efficiency enhancement within internal combustion Rankine cycle engine, while the feedback signal of close-loop direct water injection control is still absent. Ion current detection monitors in-cylinder electron variation which shows potential in revealing direct water injection process. For better understanding of unprecedented augment of ion current signal under direct water injection within internal combustion Rankine cycle engine, a chemical kinetic model is established to calculate the effect of intake oxygen fraction, fuel quantity, initial temperature and residual water vapor on in-cylinder electron formation based on GRI Mech 3.0 and ion current skeleton mechanism. The simulation results indicate direct water injection process show significant impact on in-cylinder electron formation through chemical interactions between H2O and other intermedia species including HO2, O2, CH3 and H, these reactions provides additional OH radical for propane oxidation facilitation, which result in large portion of CH radical formation and therefore, lead to higher in-cylinder electron generation. The initial temperature plays a vital role in determining whether residual water vapor show positive or negative effect by in-cylinder temperature coordination of direct water injection. Results of this work can be used to explain phenomenon related to direct water injection and ion current signal variation under both internal combustion Rankine cycle or traditional petrol engine.