Effect of Spraying Parameters on the Microstructure and Mechanical Properties of Micro-Plasma Sprayed Alumina-Titania Coatings

Electrical property of a micro-plasma spray system with different working-gas feed- ing schemes was tested to optimize the plasma spray process. The arc voltage with an integrated gas injection mode is higher than that with radial injection or axial injection modes. Thus, an integrated gas injection mode with an excellent electrical characteristic was adopted to deposit alumina-titania coating. The microstructure, bonding strength and hardness of the plasma sprayed alumina-titania coating, as a function of the spraying parameters, e.g., plasma current, gas flow rate and gas pressure, were studied. It was shown that the spraying parameters affected remarkably on the microstructure of the coating. Different tendencies in bonding strength and hardness were also shown for different spraying parameters. At an arc current of 250 A, a gas flow rate of 20 L/min and a gas pressure of 0.5 MPa, the bonding strength and micro-hardness of the coatings reach 40.6 MPa and HV1406.1, respectively.

Optimization and test for spraying parameters of cotton defoliant sprayer

Boom sprayer is widely used in large farm crops because of its high working efficiency and favorable spraying effect.But there are still some problems in cotton defoliant spraying in Xinjiang,China.Cotton is planted in a high density in Xinjiang,the row space is(10+66)cm,leaves in two adjacent rows are seriously overlapped,the lower leavers are poorly sprayed,so the defoliation effect is poor,and the cotton quality is degraded.To solve this problem and improve the defoliant droplets coverage on the cotton canopy,the original boom spraying was modified,and the spraying pardameters was optimized by the central combination test and design concept of Box-Behnken based on a single-factor test.A quadratic polynomial model of droplets coverage was created by using working parameters including horizontal spraying boom height,hang boom height and nozzles angle as the influential factors and the mean droplets coverage on cotton canopy as the target function,and the effectiveness of mode and interaction of factors were analyzed.The model was optimized and analyzed using the regression analysis method and response surface analysis method of software Design-Expert 7.0.0,and the optimal combination of spraying parameters was obtained.The results showed that the droplets coverage on cotton canopy were influenced by boom height,sprayer height and angled nozzles sequentially from large to small,and the optimal combination of spraying parameters was under horizontal spraying boom height of 134 cm,hang spraying boom height of 27.5 cm and nozzles angle of 21°.The mean droplets coverage of experimental value and predicted value on cotton canopy were 19.6%and 20.43%respectively in such conditions,and the relative error to the estimated value on the model was–4.25%.The research result can provide a reference for further optimizing the spraying parameters of cotton defoliant sprayer.

Effects of atomization parameters of dust removal nozzles on the de-dusting results for different dust sources

In order to obtain appropriate spray pressure and enhance the spraying and dust removal efficiency, various factors including the dust characteristics, nozzle spraying angle, effective spraying range, water consumption and droplet size are taken into account. The dust characteristics from different mines and atomization parameters of different pressure nozzles were measured. It was found that the internal pressure of coal cutters and roadheaders should be kept at 2 MPa, which could ensure large droplet size, large spraying angle and low water consumption and hence realizing a large-area covering and capture for large particle dusts. However, the external spray pressure should be kept at 4 MPa for smaller droplet size and longer effective spraying range, leading to effective dust removal in the operator zone. The spray pressure of support moving, drawing opening, and stage loader on a fully mechanized caving face and stage loader on a fully mechanized driving face should be kept at 8 MPa, under which the nozzles have long effective spraying range, high water flow and small droplet size for the rapid capture of instantaneous, high-concentration and small size dust groups. From the applications on the caving and driving faces in the coal mines, it is indicated that the optimization of spray pressure in different spraying positions could effectively enhance dust removal efficiency. Selecting appropriate nozzles according to the dust characteristics at different positions is also favorable for dust removal efficiency. With the selected nozzles under optimal pressures, the removal rates of both total dust and respirable dust could reach over70%, showing a significant de-dusting effect.

Adaptive spraying decision system for plant protection unmanned aerial vehicle based on reinforcement learning

To solve the problem of lacking scientific guidance in aerial pesticide application,this study introduced an adaptive spraying decision system(ASDS)for Unmanned Aerial Vehicle(UAV)spraying to guide the operators of plant protection UAVs to set reasonable spraying parameters under complicated environment.The minimum applied volume rate,proper spraying velocity,spraying height,and initial droplet size were recommended by the ASDS.The key factor of the decision system is the decision model of reinforcement learning based on the actor-critic neural network.In specific,the field experimental data were used to train the critic and actor networks,which made the model adaptive to optimize the output of spraying parameters.Compared with the conventional spraying parameters,the spraying parameters recommended by the ASDS had a positive impact on wheat parcels.The decision results of the ASDS showed that the spraying volume rate was lower in the blocks with a small leaf area index.In addition,the spraying volume rate for the whole parcel was reduced by 14%.After UAV spraying,the uniformity of the droplet deposition in the ASDS parcel was better than that in the conventional parcel.Moreover,the penetrability of the droplets and the control efficacy for the brown wheat mite Petrobia latens(Muller)were similar in the two parcels.The ASDS can recommend the optimal spraying parameters to minimize pesticide application.