In this article, a novel wideband circularly polarized (CP) square-slot antenna with perturbation elements is proposed. The antenna comprises of an inverted L-shaped feeding line, pairs of corner cuts, a rectangular slot, and a semielliptical patch. The numerous CP resonant modes were excited simultaneously using these slots and patches as perturbation elements. To verify this concept, an antenna prototype was built and tested. The measured results indicate the À10-dB impedance bandwidth (IBW) is 69. 3.7 GHz) and 3-dB axial ratio bandwidth (ARBW) is 59% (2.58-4.74, 3.66 GHz). Furthermore, the measured peak gain is 4.3 dBi, and the gain variation within the certain bandwidth is less than 1 dB. Therefore, the presented antenna features wide CPBW and stable gain characteristics.
A recursive subspace identification algorithm for autonomous underwater vehicles (AUVs) is proposed in this paper. Due to the advantages at handling nonlinearities and couplings, the AUV model investigated here is for the first time constructed as a Hammerstein model with nonlinear feedback in the linear part. To better take the environment and sensor noises into consideration, the identification problem is concerned as an errors-in-variables (EIV) one which means that the identification procedure is under general noise assumption. In order to make the algorithm recursively, propagator method (PM) based subspace approach is extended into EIV framework to form the recursive identification method called PM-EIV algorithm. With several identification experiments carried out by the AUV simulation platform, the proposed algorithm demonstrates its effectiveness and feasibility.
For the large equipment, system model is usually difficult to obtain, or changes slowly with the running time. Therefore, some methods based on accurate model are difficult to apply, such as wind turbine. Therefore, the data‐based robust value iteration method based on data is studied for variable pitch control of wind turbine for the first time, which can deal with uncertainty and do not require an accurate model. First, a new data‐driven Bellman equation is derived base on the system operation data. Next, the robust VI structure based on data is designed, which is a model free iteration algorithm. Then, a data‐driven value iteration pitch controller is proposed, the simulation results show the effectiveness of the control method.
This paper proposes a novel wideband circularly polarized (CP) dielectric resonator antenna (DRA) loaded with strips. The CP DRA comprises a circular DR, two pairs of driven L-like DR strips with different lengths, and a square ground-plane. To couple the electromagnetic energy to circular DR, an orthogonal cross-slot is used, and a stepped microstrip-line is also used to adjust the impedance matching. Influenced by the concept of deformed DR, two pairs of L-like DR strips of different lengths are inserted into the circular DR as part of the driven element to excite a new axial ratio (AR) resonant point. An antenna prototype is simulated, manufactured, and measured to validate the unique design. The measured results show that the designed antenna has broadband characteristic with a −10 dB IBW of 54% (1.91–3.32 GHz) and 3 dB ARBW of 42.1% (2.10–3.22 GHz).
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