With the salience of air pollution problems such as PM2.5, the removal of micro particle dust has increasingly become a widespread issue to address. In this study, we put forward the technology of charged water mist in vibrating fiber grid. Five types of effect of catching dust, such as gravitational settlement, inertial collision, interception, diffusion, and electrostatic attraction in a single fiber, were theoretically analyzed. The mechanism of vibration fiber grid, whose resonant film-forming effect was analyzed on spray charging water, was also studied. The infinitesimal analysis method was used for calculating the efficiency of catching dust in the vibrating fiber grid. The fiber grating arrangement was determined by performing lots of experiments of dust collection efficiency and resistance loss in longitude of fiber grating, latitude, and interlacing fiber grating. The obtained results showed that not only the dust removal in longitude of fiber grating, which was easy to use, was stable and efficient, but also the resistance loss was relatively low and the natural dust drop did not need frequent ash removal. Therefore, the charged spray in longitude of vibration fiber grating has certain application value in dust removal technology. The theoretical and experimental results also show that the technology of dust removal by charged spray in vibration fiber grid has a high purification efficiency for micro particles and simple structure and thus would have certain valuable application in dust removal technology in future.

Morphing aircraft are capable of modifying their geometry configurations according to different flight conditions to improve their performance, such as by increasing the lift-to-drag ratio or reducing their fuel consumption. In this article, we focus on the airfoil morphing of wings and propose a novel morphing control method for an asymmetric deformable airfoil based on deep reinforcement learning approaches. Firstly, we develop an asymmetric airfoil shaped using piece-wise Bézier curves and modeled by shape memory alloys. Resistive heating is adopted to actuate the shape memory alloys and realize the airfoil morphing. With regard to the hysteresis characteristics exhibited in the phase transformation of shape memory alloys, we construct a second-order Markov decision process for the morphing procedure to formulate a reinforcement learning environment with hysteresis properties explicitly considered. Subsequently, we learn the morphing policy based on deep reinforcement learning techniques where the accurate information of the system model is unavailable. Lastly, we conduct simulations to demonstrate the benefits brought by our learning implementations and validate the morphing performance of the proposed method. The simulation results show that the proposed method provides an average 29.8% performance improvement over traditional methods.

The traditional dust removal technology is difficult to meet the strict requirements of environmental protection, so it is of practical significance and research value to study how to purify fine dust in workshop. Fine dust can be suspended in the atmosphere, while reducing the air quality. Excessive inhalation of dust may result in disease. So it should be paid close attention to dust control. The water mist charging process has experienced three stages: induction charge, corona charge transition, and corona charge. When the discharge distance is 80 mm, the charge-mass ratio of droplet and the current of water mist are most affected by corona voltage. The significant impact analysis of orthogonal experiment is studied. The result of the orthogonal experiment is analyzed by the variance method. It is noted that the inlet wind speed has the highest influence, and the discharge distance has a least influence on the dust removal efficiency. The discharge distance is 80 mm, and the voltage working band is suitable for the normal voltage regulation of the electrostatic precipitator. The condensation efficiency of charged droplets on dust is beneficial to reduce the negative effect of excessive wind speed on wet vibrating string grid and to improve the effective handling volume of dust collector. The charge-mass ratio of water mist is improved effectively, and the dust removal efficiency is increased in the vibrating string filter with charged water mist. Theoretical analysis and experimental studies showed that the vibrating string filter with charged water mist is as a new composite efficient dust removal technology that can effectively deal with the purification of fine dust particles in the gas stream, especially in respiratory dust removal.

Observability analysis of a bioinspired flexible flapping wing system provides a measure of how well the states of flexible flapping wing micro-aerial vehicles can be estimated from real-time measurements during high-speed flight. However, the traditional observability analysis approaches have trouble in terms of lack of quantitative analysis index, high computational complexity, low accuracy, and unavailability in stochastic systems with memory, including bioinspired flexible flapping wing systems. Therefore, a novel derivative-free observability analysis method is proposed here based on the generalized polynomial chaos expansion. By formulating a surrogate model to represent the relationship between the cumulative measurement and the random initial state, the observability coefficient matrix is calculated and the observability rank condition is stated. Consequently, several observability indices are proposed to quantity the observability of the system. Altogether, the proposed method avoids the disadvantages of the traditional approaches, especially in assessing the observability degree of each state and the effect of stochastic noise on observability. The validation of the proposed method is first provided by demonstrating the equivalence between the traditional and proposed methods and subsequently by comparing the observability of the Lorenz system calculated via three different approaches. Finally, the proposed method is applied on a bioinspired flexible wing system to optimize the placement of sensors, which is consistent with the natural configuration of campaniform sensilla on the wing of the hawkmoth.