An effective approach is presented for pattern synthesis of reconfigurable antenna arrays with non‐uniformly spaced arrangements. On the basis of the joint sparse model of multiple reference patterns, the proposed approach can dynamically reconfigure multiple radiation patterns with exactly matched pattern details and minimum number of antenna elements by joint optimisation of element positions and excitations. In this study, the design of sparse reconfigurable arrays is recast as a simultaneous sparse approximation problem and solved with the multi‐task Bayesian compressive sensing. The common element positions and individual element excitations for multiple radiation patterns are obtained simultaneously by searching out multiple weight vectors sharing the same prior probability. Several representative experiments are provided to validate the effectiveness of the proposed method for the design of maximally sparse reconfigurable antenna arrays with exact pattern matching.
Coating a heterogeneous layer outside the core nanoparticles has become a common method to protect the properties of nanoparticles and may extend the application range of core nanoparticles. Rare earth ion-doped nanoparticles NaYF4:Yb 3+ ,Er 3+ is one of the most efficient up-conversion nanosystems. In this work, a multi-functional NaYF4:Yb 3+ ,Er 3+ @TiO2 core-shell structure nanocomposite was synthesized. The structure, optical and photoluminescence properties of the up-converting nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and room temperature up-conversion luminescence (UCL) spectrofluorimetric measurements.
Dynamic performance of high speed dynamic balancing machine directly affects the accuracy and safety of dynamic balancing machine. ANSYS 12.0 was used to establish the frame structure model in this paper. The four models of dynamic balancing machine were calculated respectively. The calculation results show that additional stiffness can greatly improve the natural frequencies of dynamic balancing machine. In addition, as the base is large, we can ignore the influence on natural frequencies caused by the base.
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