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The paper proposed a boost five-level inverter for wireless power transfer (WPT) system. It consists of one DC source, one inductor, one capacitor, and six power switches. It can produce a five-level output with an amplitude twice that of the DC source voltage. Compared with the existing five-level inverters, the proposed topology needs fewer power switches and energy storage elements, as well as lower power switches total standing voltage. Firstly, this paper introduced the topology and operating principle of the proposed inverter, established the mathematical models of the inverter output voltage and the system output power, and compared the proposed inverter with the existing five-level inverters. On this basis, the level cascaded extension method and topology of the proposed inverter were introduced and analyzed. Then, the modulation strategy and parameters of the proposed inverter were designed. Furthermore, the power loss of the proposed inverter was calculated. Finally, simulation and experimental verification were conducted. The results show that the inverter efficiency can reach up to about 94.5%, and the output THD can be as low as 24.47% or even lower. In addition, the transient response time is within 4 ms, proving the feasibility and superiority of the proposed inverter applied to WPT systems. [ABSTRACT FROM AUTHOR]

In this paper, we apply the fixed-point theorems of γ concave and − γ convex operators to establish the existence of positive solutions for fractional differential systems with multipoint boundary conditions. Two examples are given to support our results. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we use the monotone iterative technique combined with cone theory to investigate the existence of solutions to the Cauchy problem for Caputo fractional differential equations in Banach spaces. New existence theorems are obtained for the case of a cone being normal and fully regular respectively. Moreover, two examples are given to illustrate the abstract results. [Copyright &y& Elsevier]

Two new Ni(II) complexes of 2,6-bis[1-(2,6-diethylphenylimino)ethyl]pyridine (L1), 2,6-bis[1-(4-methylphenylimino)ethyl]pyridine (L2) have been synthesized and structurally characterized. Complex Ni(L1)Cl2 · CH3CN (1), exhibits a distorted trigonal bipyramidal geometry, whereas complex Ni(L1)(CH3CN)Cl2 (2), is six-coordinate with a geometry that can best be described as distorted octahedral. The catalytic activities of complexes 1, 2, Ni{2,6-bis[1-(2,6-diisopropyl-phenylimino)ethyl]pyridine} Cl2 · CH3CN (3), and Ni{2,6-bis[1-(2,6-dimethylphenylimino) ethyl]pyridine}Cl2 · CH3CN (4), for ethylene polymerization were studied under activation with MAO. [ABSTRACT FROM AUTHOR]

Stimulated Brillouin scattering (SBS), a fundamental nonlinear interaction between light and acoustic waves occurring in any transparency material, has been broadly studied for several decades and gained rapid progress in integrated photonics recently. However, the SBS noise arising from the unwanted coupling between photons and spontaneous non-coherent phonons in media is inevitable. Here, we propose and experimentally demonstrate this obstacle can be overcome via a method called orbital angular momentum mode division filtering. Owing to the introduction of a new distinguishable degree-of-freedom, even extremely weak signals can be discriminated and separated from a strong noise produced in SBS processes. The mechanism demonstrated in this proof-of-principle work provides a practical way for quasi-noise-free photonic-phononic operation, which is still valid in waveguides supporting multi-orthogonal spatial modes, permits more flexibility and robustness for future SBS devices. [ABSTRACT FROM AUTHOR]

We propose a grating semi-feedback external cavity (GSFEC) scheme for high-power broad-area laser diodes for improving the spectrum characteristics of high-power semiconductor lasers. We design this scheme as two crossed cylindrical resonators employing a holographic diffraction grating and a rectangular highly reflecting mirror. In our experiments, we obtain stable spectrum characteristics over a tuning range of 5 nm, with maximum output power up to 764 mW at an operating current of 3.5 A. The wavelength drift rate with injection current decreases from 0.59 nm/A of free-running condition to 0.2 nm/A, and the laser bandwidth is compressed to 21.5% at 2 A. [ABSTRACT FROM AUTHOR]