Hengsheng Tang

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We establish conditions for the existence of periodic solutions of nonlinear, second-order difference equations of the form y(t + 2) + by(t + 1) + cy(t) = f (y(t)), where c = 0 and f : R → R is continuous. In our main result we assume that f exhibits sublinear growth and that there is a constant β > 0 such that u f (u) > 0 whenever |u| ≥ β. For such an(More)
A semi-weakly confined waveguide structure was designed and fabricated. This waveguide structure has a 350 nm thin core layer. Its optical mode field is weakly confined in vertical direction but is strongly confined laterally. The waveguide can support a nearly circular optical field distribution that matches well with a single-mode fiber. An erbium-doped(More)
This paper aims to show the existence of nontrivial solutions for discrete elliptic boundary value problems by using the " Mountain Pass Theorem ". Some conditions are obtained for discrete elliptic boundary value problems to have at least two nontrivial solutions. The results obtained improve the consequences of the known literature [Guang Zhang, Existence(More)
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