CiteULike: norris's Luo

Design and analytical full-wave validation of the invisibility cloaks, concentrators, and field rotators created with a general class of transformations

Yu Luo — 2008-06-18T10:00:36-00:00

Physical Review B (Condensed Matter and Materials Physics), Vol. 77, No. 12. (2008)

We investigate a general class of electromagnetic devices created with any continuous transformation functions by rigorously calculating the analytical expressions of the electromagnetic field in the whole space. Some interesting phenomena associated with these transformation devices, including the invisibility cloaks, concentrators, and field rotators, are discussed. By carefully choosing the transformation function, we can realize cloaks, which are insensitive to perturbations at both the inner and outer boundaries. Furthermore, we find that when the coating layer of the concentrator is realized with left-handed materials, energy will circulate between the coating and the core, and the energy transmitted through the core of the concentrator can be much bigger than that transmitted through the concentrator. Therefore, such concentrator is also a power flux enhancer. Finally, we propose a spherical field rotator, which functions as not only a wave vector rotator but also a polarization rotator, depending on the orientations of the spherical rotator with respect to the incident wave direction. The functionality of these transformation devices are all successfully confirmed by our analytical full-wave method, which also provides an alternate computational efficient validation method in contrast to numerical validation methods.

The impedance-matched reduced acoustic cloaking with realizable mass and its layered design

Huan-Yang Chen — 2008-05-13T13:18:20-00:00

(8 May 2008)

The authors present an impedance-matched reduced version of acoustic cloaking whose mass is in a reasonable range. A layered cloak design with isotropic material is also proposed for the reduced cloak. Numerical calculations from the transfer matrix methods show that the present layered cloak can reduce the scattering of an air cylinder substantially.

On Conditions at an Interface between Two Materials in Three-Dimensional Space

L Wheeler — 2008-05-06T12:45:29-00:00

Mathematics and Mechanics of Solids, Vol. 4, No. 2. (1 June 1999), pp. 183-200.

This article is concerned with expressing the kinematics of a bimaterial-bonded interface in terms of strains in the three-dimensional case. It is shown that the continuity of displacements can be replaced by the requirement that the change in principal curvatures, the mean geodesic torsion, and the interior strains be matched across the interface. The reduction of these conditions for a two-dimensional bonded interface is also discussed. 10.1177/108128659900400203

Controlling the Emission of Electromagnetic Sources by Coordinate transformation

Yu Luo — 2008-03-10T12:31:21-00:00

(21 Dec 2007)

The coordinate transformation on the space that contains electromagnetic sources is studied. We find that, not only the permittivity and permeability tensors of the media, but also the sources inside the media will take another form in order to behave equivalently as the original case. It is demonstrated that, a source of arbitrary shape and position in the free space can be replaced by an appropriately designed metamaterial coating with current distributed on the inner surface and would not be detected by outer observers, because the emission of the source can be controlled at will in this way. As examples, we show how to design conformal antennas by covering the sources with transformation media. The method proposed in this letter provides a completely new approach to develop novel active EM devices.

Cloak for multilayered and gradually changing media

Jingjing Zhang — 2008-02-04T19:21:40-00:00

Physical Review B (Condensed Matter and Materials Physics), Vol. 77, No. 3. (2008)

Coordinate transformation approach has previously been used for designing a cloak which can shield an interior region in a homogeneous medium. In this paper, we consider the case where the background is no longer a homogeneous medium and determine the relative constitutive parameters of the cloak according to the multilayered and gradually changing background. We propose the parameters of cylindrical cloak structures working in multilayered and gradually changing media and the scheme of specifying these parameters could also be applied to the design of a cloak in an arbitrary isotropic background. The theoretical analysis based on coordinate transformation is given and numerical simulations are performed to illustrate these properties. The simulation results show that the cloaking with the proposed parameters performs well in these inhomogeneous background medium. Potential applications are also discussed.

On the stress-based and strain-based methods for predicting optimal orientation of orthotropic materials

HC Gea — 2006-11-13T16:41:12-00:00

Structural and Multidisciplinary Optimization, Vol. V26, No. 3. (1 February 2004), pp. 229-234.