Renal complications of lipodystrophy: A closer look at the natural history of kidney disease

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/144612/1/cen13732_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144612/2/cen13732.pd

Near-field imaging with metamaterial: deconvolution of an image using SVD

A deconvolution procedure based on the Array Scanning Method and the Singular Value Decomposition is presented to capture a source distribution from an image affected by white noise. The image is obtained using a collimating metamaterial made of infinite, doubly periodic array of silver nanorods with the help of the Array Scanning Method. The numerical results show that the source distribution can be captured from the image by tuning the threshold in SVD used for inversion, hence by selecting a proper source subspace

On the relationship between multiple-scattering Macro Basis Function and Krylov subspace iterative methods

A mathematical link is provided between the Krylov subspace iterative approach based on the full orthogonalization method (FOM) and the macro basis functions (MBF) approach based on a multiple-scattering methodology. The link refers to the subspaces created by those methods as well as to the orthogonality conditions which they satisfy. Both approaches are applied to the same method-of-moments (MoM) system of equations that is preconditioned based on a closest-interaction rule, and where blocks of the MoM impedance matrix are compressed using a rank-revealing method. MBF and FOM approaches are compared numerically, with a special attention given to accuracy, for perfectly conducting objects, comprising an array of tapered-slot antennas, spheres and an aircraft. The respective advantages of both methods are briefly discussed and further prospects are given

On the Relationship between Finite and Infinite Arrays in the Context of Radiation and Scattering Problems

A fast technique for Finite Array analysis applicable to metallic as well as printed antennas is proposed using an Infinite Array approach. In view of that, the Dyadic form of Periodic Array Green's function for the case of dielectric medium are computed in spectral domain. The extraction of the periodic singularities is carried out by subtracting the contribution from an Infnite Array solution for an average medium in space-spectral domain with exponential convergenc

A Near-Field Preconditioner Preserving theLow-Rank Representation of Method of MomentsInteraction Matrices

A preconditioning methodology is proposed to preserve the low-rank representation of Method-of-Moments interaction matrix blocks in the context of multiple-scattering-based Macro Basis Function methodology. The scatterer is divided into sub-domains that can be connected with each other. A low-rank representation is obtained by employing the incomplete QR factorization without constructing the interaction matrix blocks a priori. Performing compression before preconditioning allows one to change at will the preconditioning technique. The preconditioning considered in this study is based on nearest interactions and involves auxiliary sub-domains which are immediately connected with the sub-domain of interest and partially overlap neighboring sub-domains. Low-rank representation of the interaction matrices is preserved by dealing with the auxiliary sub-domains separately. This approach comes at the cost of an overhead in terms of memory, which is directly connecte

Compact Mathematical Description of Sectorially Symmetrical Arrays

The proposed approach is being developed in the framework of compact direction-finding systems that include polarization estimation. This work concentrates on sectorially symmetrical arrays, and combines the classical Array Scanning Method (ASM) with a Spherical Waves Decomposition (SWD) in order to directly compute the SWD coefficients based on the ASM current distributions. This approach offers the advantages of a fast computation based on the current distribution on only one antenna, as well as a reduced set of parameters needed to evaluate the embedded element patterns

Numerically stable eigenmode extraction in 3-D periodic metamaterials

A numerical method is presented to compute the eigenmodes supported by 3-D metamaterials using the method of moments. The method relies on interstitial equivalent currents between layers. First, a parabolic formulation is presented. Then, we present an iterative technique that can be used to linearize the problem. In this way, all the eigenmodes characterized by their transmission coefficients and equivalent interstitial currents can be found using a simple eigenvalue decomposition of a matrix. The accuracy that can be achieved is limited only by the quality of simulation, and we demonstrate that the error introduced when linearizing the problem decreases doubly exponentially with respect to the time devoted to the iterative process. We also draw a mathematical link and distinguish the proposed method from other transfer-matrix-based methods available in the literature