Research on Airspace Planning for Stand-off and Compound Jamming

Abstract

A radar adopts anti-jamming techniques such as side lobe cancellation and moving target indication, resulting in the worsening of the effects of single active jamming and passive jamming. Therefore a compound jamming strategy was proposed and can effectively respond to the anti-jamming device of the new radar. The conditions for the use of this strategy were defined. Based on the military airspace planning principles, taking into account human error, wind and other errors, the specific process of airspace planning was elaborated. Taking into account the effects of compound jamming and the safety of a jammer, an airspace model for stand-off and compound jamming was established. The Whale Optimization Algorithm (WAO) with Tent chaotic sequence was used to solve the model and the airspaces with different preferences were planned. The simulation results show that the model is scientific and effective. The optimization ability of the WOA of with tent chaotic sequence is better than WAO. In addition, the planning direction is quite different in Simulation 1 and Simulation 2, with a maximum of 99°. The compound jamming for stand-off jamming in airspace planning is more flexible and has more advantages in multiple military planning airspaces.

Effect of meso‐structure characteristics on surface emissivity of 2.5D Woven ablative composite for thermal protection

“…where the subscripts in and out represent radiation from air striking to tows and radiation from tows to air. It shows that the input radiation from semitransparent air strikes to surfaces of fiber tows (the first term of the right T A B L E 1 Emissivity of fiber tows with temperature [53] T side) and then is reflected (the second term of the right side). There is no penetration through boundaries so that…”

“…Subscripts in and out represent inward and outward direction of radiation. Reflectivity is calculated by T A B L E 3 Material properties of aluminum oxide [53,54] Property Unit Value…”

“…In woven ablative composites, radiation mainly occurs from fiber tows and radiates outward upper surface of composite, which means that the tows close to the upper surface of meso-scale region contribute more energy ρ tow kg/m 3 1800 [56] ρ air kg/m 3 1.293 [52] ε char -0.85 [52] ε tow -Table 2 [53] toward surface. For simplification of simulation, the number of layers of meso-scale region should be determined.…”

Study on Corrosion Fatigue Properties of the Welded Joints of SMA490BW Weathering Steel

“…When the bogie operates in the marine climate environment, the fatigue resistance may be reduced due to the action of the corrosive medium, resulting in corrosion fatigue. Corrosion fatigue is the phenomenon of crack formation and propagation under the interaction of alternating loads and corrosive media [3]. Corrosion fatigue can occur in materials that are sensitive or insensitive to stress corrosion, so no single alloy is resistant to corrosion fatigue [3].…”

“…Corrosion fatigue is the phenomenon of crack formation and propagation under the interaction of alternating loads and corrosive media [3]. Corrosion fatigue can occur in materials that are sensitive or insensitive to stress corrosion, so no single alloy is resistant to corrosion fatigue [3]. At present, the research on MAG welded joints of SMA490BW steel mainly focuses on the welding process, microstructure, mechanical properties [4], fatigue properties [5] and salt spray corrosion [6], but there are few studies on its corrosion fatigue properties.…”