arXiv subjects

Xue Jiang

Publications and source records attributed to Xue Jiang.

117 records · Page 7Linked to original sources

arXiv2016

Inverse Electromagnetic Diffraction by Biperiodic Dielectric Gratings

Consider the incidence of a time-harmonic electromagnetic plane wave onto a biperiodic dielectric grating, where the surface is assumed to be a small and smooth perturbation of a plane. The diffraction is modeled as a transmission problem for Maxwell's equations in three dimensions. This paper concerns the inverse diffraction problem which is to reconstruct the grating surface from either the diffracted field or the transmitted field. A novel approach is developed to solve the challenging nonlinear and ill-posed inverse problem. The method requires only a single incident field and is realized via the fast Fourier transform. Numerical results show that it is simple, fast, and stable to reconstruct biperiodic dielectric grating surfaces with super-resolved resolution.

math.NA↗

arXiv2016

Convergence of the PML solution for elastic wave scattering by biperiodic structures

This paper is concerned with the analysis of elastic wave scattering of a time-harmonic plane wave by a biperiodic rigid surface, where the wave propagation is governed by the three-dimensional Navier equation. An exact transparent boundary condition is developed to reduce the scattering problem equivalently into a boundary value problem in a bounded domain. The perfectly matched layer (PML) technique is adopted to truncate the unbounded physical domain into a bounded computational domain. The well-posedness and exponential convergence of the solution are established for the truncated PML problem by developing a PML equivalent transparent boundary condition. The proofs rely on a careful study of the error between the two transparent boundary operators. The work significantly extend the results from the one-dimensional periodic structures to the two-dimensional biperiodic structures. Numerical experiments are included to demonstrate the competitive behavior of the proposed method.

math.NA↗

arXiv2016

A new 2D monolayer BiXene, M2C (M=Mo, Tc, Os)

Note this is a rather coarse version of our manuscript since uploading tex files are necessary (we are not willing to upload all tex files). The existence of BiXenes, a new family of 2D monolayers is here predicted. Theoretically, BiXenes have 1H symmetry (P-6m2) and can be formed from the 4d/5d binary carbides. As the name suggests, they are close relatives of MXenes, which instead have 1T symmetry (P-3m1). The newly found BiXenes, as well as some new MXenes, are shown to have formation energies close to that of germanene, which suggests that these materials should be possible to be synthesised. Among them, we illustrate that 1H-Tc2C and 1T-Mo2C are dynamically stable at 0 K, while 1H-Mo2C, 1TTc2C, 1H-Tc2C, and 1T-Rh2C are likely to be stabilised via strain or temperature. In addition, the nature of the chemical bonding is analysed, emphasizing that the covalency between the transition metal ions and carbon is much stronger in BiXenes than in MXenes. The emergence of BiXenes can not only open up a new era of conducting 2D monolayers, but also provide good candidates for carrier materials aimed at energy storage and spintronic devices that have already been unveiled in MXenes.

cond-mat.mtrl-sci↗

arXiv2016

Error Formulas for Ideal Interpolation

In this paper we study the algebraic structure of error formulas for ideal interpolation. We introduce the so-called "normal" error formulas and prove that the lexicographic order reduced Gröbner basis admits such a formula for all ideal interpolation. This formula is a generalization of the "good" error formula proposed by Carl de Boor. Finally, we discuss a Shekhtman's example and give an explicit form of "normal" error formula for this example.

math.NA↗

arXiv2016

An adaptive finite element PML method for the elastic wave scattering problem in periodic structures

An adaptive finite element method is presented for the elastic scattering of a time-harmonic plane wave by a periodic surface. First, the unbounded physical domain is truncated into a bounded computational domain by introducing the perfectly matched layer (PML) technique. The well-posedness and exponential convergence of the solution are established for the truncated PML problem by developing an equivalent transparent boundary condition. Second, an a posteriori error estimate is deduced for the discrete problem and is used to determine the finite elements for refinements and to determine the PML parameters. Numerical experiments are included to demonstrate the competitive behavior of the proposed adaptive method.

math.NA↗

arXiv2014

Experimental realizations of full control of reflected waves with subwavelength acoustic metasurfaces

Metasurfaces with subwavelength thickness have exhibited unconventional phenomena in ways that could not be mimicked by traditional materials. Here we report the analytical design and experimental realizations of acoustic metasurface with hitherto inaccessible functionality of manipulating the reflected waves arbitrarily. By suitably designing the phase shift profile covering 2 range induced by labyrinthine units, the metasurface can reflect acoustic waves in an unusual yet controllable manner. Anomalous reflection and ultrathin planar lens with adjustable focal point were both demonstrated with carefully designed metasurfaces. Remarkably, the free manipulation of phase shifts offers great flexibility in the design of non-paraxial or paraxial acoustic self-accelerating beams with arbitrary trajectories. With the extraordinary wave-steering ability, the metasurface should open exciting possibilities for designing compact acoustic components with versatile potential and may find a variety of applications ranging from ultrasound imaging to field caustic engineering.

cond-mat.mtrl-sci↗

arXiv2014

Ultra-Broadband Acoustic Metasurface for Manipulating the Reflected Waves

We have designed and experimentally realized an ultra-broadband acoustic metasurface (UBAM) capable of going beyond the intrinsic limitation of bandwidth in existing designs of optical/acoustical metasurfaces. Both the numerical and experimental results demonstrate that the UBAM made of subwavelength gratings can manipulate the reflected phase-front within a bandwidth larger than 2 octaves. A simple physical model based on the phased array theory is developed for interpreting this extraordinary phenomenon as well as obtaining deeper insight to the underlying physics of our design. We anticipate the UBAM to open new avenue to the design and application of broadband acoustical devices.

cond-mat.mtrl-sci↗

arXiv2014

The Breadth-one $D$-invariant Polynomial Subspace

We demonstrate the equivalence of two classes of $D$-invariant polynomial subspaces introduced in [8] and [9], i.e., these two classes of subspaces are different representations of the breadth-one $D$-invariant subspace. Moreover, we solve the discrete approximation problem in ideal interpolation for the breadth-one $D$-invariant subspace. Namely, we find the points, such that the limiting space of the evaluation functionals at these points is the functional space induced by the given $D$-invariant subspace, as the evaluation points all coalesce at one point.

math.NA↗

arXiv2014

Broadband omnidirectional invisibility for sound in three dimensions

Acoustic cloaks that make object undetectable to sound waves have potential applications in a variety of scenarios and have received increasing interests recently. However, the experimental realization of a three-dimensional (3D) acoustic cloak that works within broad ranges of operating frequency and incident angle still remains a challenge despite the paramount importance for the practical application of cloaking devices. Here we report the design and experimental demonstration of the first 3D broadband cloak capable of cancelling the scattering field near curved surfaces. Unlike the ground cloaks that only work in the presence of a flat boundary, the proposed scheme can render the invisibility effect for an arbitrarily curved boundary. The designed cloak simply comprises homogeneous positive-index anisotropic materials, with parameters completely independent of either the cloaked object or the boundary. With the flexibility of applying to arbitrary boundaries and the potential of being extended to yield 3D acoustic illusion effects, our method may take major a step toward the application of acoustic cloaks in reality and open the avenue to build other acoustic devices with versatile functionalities.

physics.class-ph↗