We analyze, both analytically and numerically, the effectiveness of cloaking an infinite cylinder from observations by electromagnetic waves in three dimensions. We show that, as truncated approximations of the ideal permittivity and permeability tensors tend towards the singular ideal cloaking fields, so that the anisotropy ratio tends to infinity, the D and B fields blow up near the cloaking surface. Since the metamaterials used to implement cloaking are based on effective medium theory, the resulting large variation in D and B will pose a challenge to the suitability of the field averaged characterization of " and 碌. We also consider cloaking with and without the SHS (softand- hard surface) lining, shown in [6] to be theoretically necessary for cloaking in the cylindrical geometry. We demonstrate numerically that cloaking is significantly improved by the SHS lining, with both the far field of the scattered wave significantly reduced and the blow up of D and B prevented.
标签： effectiveness analytically numerically cloaking
上传时间： 2017-03-30
上传用户：zxc23456789
传统的基于位置信息的服务（LBS）的隐私保护需要LBS提供者（简称LSP）与用户之间通过第三方作为中介来进行信息交换，但这种模式极易遭到攻击者攻击。为此提出一种基于K-匿名机制的隐形空间算法KABSCA（k-anonymity based spatial cloaking algorithm ），通过移动设备独立建立一个分布式网络直接与LSP通讯进而避免了第三方的安全威胁。仿真实验显示:使用这种算法，用户可以享受到高质量的信息服务以及高度的隐私保护。
上传时间： 2013-11-05
上传用户：540750247
A new type of cloak is discussed: one that gives all cloaked objects the appearance of a flat conducting sheet. It has the advantage that none of the parameters of the cloak is singular and can in fact be made isotropic. It makes broadband cloaking in the optical frequencies one step closer.
标签： appearance discussed cloaked objects
上传时间： 2017-03-30
上传用户：rishian
