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A decision-making environment is full of uncertainty and complexity. Existing tools include fuzzy sets, soft sets, intuitionistic fuzzy sets, Pythagorean fuzzy sets (PFSs) and so on. Compared with intuitionistic fuzzy sets (IFSs), PFSs proposed by Yager have advantages in handling vagueness in the real world and possess good symmetry. The entropy measure is the most widespread form of uncertainty measure. In this paper, we improve the technique for order preference by similarity to an ideal solution (TOPSIS) method to better deal with multiple-attribute group decision making (MAGDM) problems based on Pythagorean fuzzy soft sets (PFSSs). To better determine the weights of attributes, we firstly define a novel Pythagorean fuzzy soft entropy which is more reasonable and valid. Meanwhile the entropy has good symmetry. Entropy for PFSSs which is used to determine the subjective weights of attributes is also defined. Then we introduce a measure to calculate integrated weights by combining objective weights and subjective weights. Based on the integrated weights, the TOPSIS method is generalized and improved to solve the MAGDM problem. A distance measure taking into account the characteristics of Pythagorean fuzzy numbers (PFNs) is used to calculate distance between alternatives and ideal solutions. Finally, the proposed MAGDM method is applied in the case of selecting a missile position. Compared with other methods, it is shown that the proposed method can rank alternatives more reasonably and have higher distinguishability.

Separation in compressor cascade triggers flow loss and instability. This paper presents a passive flow control method by introducing a slot into the blade. The slot induces self-adapted jet, while the jet flow is used to suppress cascade’s separation. To study the flow control effect, experiments were conducted and flow field details were given by validated numerical simulations. The results show that a well-designed slot carries adequate jet airflow from pressure side (PS) to suction side (SS) due to the great pressure fall between the two sides. The jet airflow delays suction side separation within specific incidence angles, so the performance of cascade achieves considerable improvements. It enables to be concluded that the slot carries jet flow to SS separation zone, and then the self-adapted jet flow re-energizes low momentum fluid and suppresses vortices in the separation which are negative to the cascade flow.

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