Due to the broadcast nature of wireless communication, it is vulnerable to malicious jamming attacks. Meanwhile, multiple users need to share the limited spectrum resources to enhance the spectrum utilization efficiency because of the scarcity of wireless spectrum resources. Therefore, wireless communication systems need to deal with the malicious jamming attacks and mutual interference among different users. In this paper, a multi-user anti-jamming grouping approach based on a coalition formation game is studied. The proposed approach can maximize users’ transmission rate while avoiding channel jamming through optimization of the coalition formation strategy under the influence of malicious jamming. With the help of the exact potential energy game, we demonstrate that the proposed game model can obtain stable Nash equilibrium solutions. Lastly, the effectiveness of the proposed algorithm is demonstrated through numerical.

In the development process of high-speed aircraft, the head of the aircraft is subject to high temperatures and high speed flows, supporting the maximum heat flow and thus requiring a reliable cooling system. A new type of head cooling system is proposed herein. An internal flow channel model of the heat transfer in a ball head made from high-temperature alloy steel is constructed, then an experimental platform is built to carry out relevant experiments on the performance of this cooling system. Firstly, the influence of different experimental conditions on the cooling efficiency of the ball head is studied. For given liquid-nitrogen supply pressure, a higher heating heat flux density on the outer surface of the ball head corresponds to higher cooling efficiency. Then, the vaporisation effect under different experimental conditions is evaluated using temperature sensors at the inlet and outlet of the ball head heat exchange channel in combination with images of the visualised glass tube. It is found that liquid nitrogen can vaporise completely when flowing through the heat exchange channel. The characteristics of the heating effect and liquid nitrogen injection for the ball head were evaluated using an infrared camera. Finally, under different experimental conditions of liquid-nitrogen supply pressure, it is found that liquid nitrogen can vaporise completely in each case, and the total temperature of the vaporised nitrogen is about 300K. It can thus be collected as a secondary gas source.