Low temperature, high alkali metal, and water content flue gas in biomass boilers restrict the application of traditional NO x treatment technology (i.e., selective noncatalytic reduction and selective catalytic reduction). In this paper, the coupled ozonation and wet absorption technology was used in a 130 t/h biomass circulating fluid bed boiler. Key parameters, that is, O 3 /NO molar ratio, mixing uniformity, liquid/gas ratio, and O 3 residual, were investigated with the industrial real case. The higher O 3 /NO molar ratio achieved better denitration efficiency, and the O 3 residual started to increase once the O 3 /NO molar ratio exceeded 2.1. Mixing uniformity is a key factor for the diffusion of ozone in flue gas, and it would directly influence N 2 O 5 formation and O 3 decomposition process. In the slurry, NO 3 − and SO 4 2− were the major byproducts after NO x and SO 2 absorption. With the optimization of key parameters, the NO x emission was controlled below 50 mg/Nm 3 under 34.8 kg/h O 3 dosage.

The effect of ultrasonic vibration on the springback effect and surface property for ultrasonic-assisted incremental sheet forming of aluminum alloy were discussed. A series of experiments were established to explore the ultrasonic vibration on the surface property and springback effect of symmetrical aluminum alloy sheet in order to facilitate analysis of experimental results. It is obtained that the application of ultrasonic vibration can reduce the springback effect. The surface waviness feature aluminum alloy becomes weaker with the continuous increase of ultrasonic amplitude and the surface topography tends to be smoother. In addition, the application of ultrasonic vibration can reduce the surface hardness and promote the surface residual stress distribution to be more uniform. The findings provide an experimental basis for further investigation of the mechanisms of the ultrasonic-assisted incremental sheet forming process.

Unmanned surface vehicle (USV) path planning is a crucial technology for achieving USV autonomous navigation. Under global path planning, dynamic local obstacle avoidance has become the primary focus for safe USV navigation. In this study, a USV autonomous dynamic obstacle avoidance method based on the enhanced velocity obstacle method is proposed in order to achieve path replanning. Through further analysis of obstacles, the obstacle geometric model set in the conventional velocity obstacle method was redefined. A special triangular obstacle geometric model was proposed to reconstruct the velocity obstacle region. The collision time was predicted by fitting the previously gathered data to the detected obstacle’s distance, azimuth, and other relevant data. Then, it is combined with the collision risk to determine when obstacle avoidance should begin and end. In order to ensure safe driving between path points, the international maritime collision avoidance rules (COLREGs) are incorporated to ensure the accuracy of obstacle avoidance. Finally, through numerical simulations of various collision scenarios, it was determined that, under the assumption of ensuring a safe encounter distance, the maximum change rates of USV heading angle are optimized by 17.54%, 58.16%, and 28.63% when crossing, head-on, and overtaking, respectively. The results indicate that, by optimizing the heading angle, the enhanced velocity obstacle method can avoid the risk of ship rollover caused by an excessive heading angle during high-speed movement and achieve more accurate obstacle avoidance action in the event of a safety encounter.

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