j. y. kim

The cloud model is one of the mathematical tools that realize the transformation of quantitative information from qualitative data. Therefore, cloud model theory is widely used in computer science, reliability estimation, nonlinear function approximation, controller design, etc. In general, cloud controller design is known to use Gaussian membership clouds. However, it is computationally expensive because membership cloud computing is a nonlinear operation, and it has a disadvantage that it is difficult to decompose the structure of the controller. This paper proposes a new asymmetric triangular cloud model consisting of linear operations instead of Gaussian functions and, on this basis, develops a controller design method to approximate the output of the controlled plant to the desired value. Furthermore, it is demonstrated that the proposed controller is capable of stability analysis even if the mathematical model of the plant is not given, and it is validated by simulation of electrode up and down control of ultra-high power electric arc furnace and stabilization control of inverted pendulum.

This study experimentally investigated various spraying modes in electrospraying, an atomization method in which a high voltage is applied to the auxiliary device at the tip of the nozzle. The spraying modes were generated depending on the experimental parameters (voltage, current, and flow rate) and characteristics of two test solutions (S and C), which were a mixture of ethanol, glycerol, citric acid, and water. Solution C had a higher electrical conductivity than solution S. Eleven spray modes were identified in the study. From a comparison of the spray modes, a maximum Sauter mean diameter (SMD) of the cone jet of solution S was 1.7 times that of solution S. The standard deviation of SMD for the unstable, rotating-jet, and pulsed-jet modes were more than two times that for the cone-jet mode. With an increase in flow rate in the cone jet, the SMD and SMD standard deviation of solution C increased linearly, and the SMD value of solution C was ~5% lower than that of solution B. The SMD standard deviations for both S and C solutions were small at low flow rates, and the standard deviation for solution C (with high conductivity) was smaller than that of solution S. For a given SMD, the current associated with solution C was higher than that associated with solution S. The study presented the comprehensive data for SMD, SMD standard deviation, and current in an electrospray system for the two fluids of different electrical conductivities under various experimental conditions.