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The attenuation of electromagnetic (EM) waves in unmagnetized plasma generated by an inductively coupled plasma (ICP) actuator has been investigated both theoretically and experimentally. A numerical study is conducted to investigate the propagation of EM waves in multilayer plasma structures which cover a square flat plate. Experimentally, an ICP actuator with dimensions of 20 cm×20 cm×4 cm is designed to produce a steady plasma slab. The attenuation of EM waves in the plasma generated by the ICP actuator is measured by a reflectivity arch test method at incident waves of 2.3 GHz and 10.1 GHz, respectively. A contrastive analysis of calculated and measured results of these incident wave frequencies is presented, which suggests that the experiment accords well with our theory. As expected, the plasma slab generated by the ICP actuator can effectively attenuate the EM waves, which may have great potential application prospects in aircraft stealth.

An improved ambiguity function method (AFM) for GPS attitude determination is presented. The new algorithm is a combination of an analytical resolution and the AFM. The first part of the algorithm is capable of reducing the search integer space by solving a dual nonlinear coupled equation, while the second resolves the adaptive function within the analytical solutions space. Static and kinematic experiments are performed to demonstrate the feasibility of the new algorithm in terms of accuracy, reliability and computation load. Comparisons to traditional algorithm and other measurement tools are given.

The inertial navigation system (INS) has been playing a prominent role in space navigation applications. However, the selected order of conventional integration schemes limits the computational accuracy of the strapdown INS (SINS) and its availability during different mission phases of space flight. A space-oriented SINS scheme, based on modern multispeed (two/three-speed) algorithms, is implemented in this paper to meet the increasing space navigation requirement. Instructive guidelines are proposed to promote the practical realization and computational efficiency of the improved scheme in space SINSs. Making use of Monte Carlo simulation, both the multispeed scheme and the conventional one are evaluated. Performance comparison between the algorithms indicates that the attitude algorithms associated with both schemes have the same degree of accuracy in the test scenario, and three times accuracy improvement is verified involving the velocity and position algorithms of the multispeed scheme in comparison with those of the conventional one.