Toward Superlensing With Metal-Dielectric Composites And Multilayers, 2009 University of Michigan - Ann Arbor
Toward Superlensing With Metal-Dielectric Composites And Multilayers, Rasmus Nielsen, Mark Thoreson, Weiqiang Chen, Anders Kristensen, Jørn Hvam, Vladimir Shalaev, Alexandra Boltasseva
We report on the fabrication of two types of adjustable, near-field superlens designs: metal–dielectric composites and metal–dielectric multilayer films. We fabricated a variety of films with different materials, thicknesses and compositions. These samples were characterized physically and optically to determine their film composition, quality, and optical responses. Our results on metal–dielectric composites indicate that although the real part of the effective permittivity generally follows effective medium theory predictions, the imaginary part does not and substantially higher losses are observed. Going forward, it appears that multilayer metal–dielectric designs are more suitable for sub-diffraction imaging applications because they ...
Hybrid Approach For Brain Tumor Segmentation In Magnetic Resonance Images Using Cellular Neural Networks And Optimization Techniques, 2009 University of Nevada, Las Vegas
Hybrid Approach For Brain Tumor Segmentation In Magnetic Resonance Images Using Cellular Neural Networks And Optimization Techniques, D. Selvathi, Henry Selvaraj, S. Thamarai Selvi
Tumor segmentation from brain magnetic resonance image data is an important but time consuming task performed manually by medical experts. Automating this process is challenging due to the high diversity in appearance of tumor tissue among different patients and in many cases, similarity between tumor and normal tissue. This paper deals with an efficient segmentation algorithm for extracting brain tumors in magnetic resonance images using Cellular Neural Networks (CNN). Learning CNN templates values are formulated as an optimization problem. The template coefficients (weights) of an CNN which will give a desired performance, can be derived by learning genetic algorithm and ...
Fabrication And Optical Characterizations Of Smooth Silver-Silica Nanocomposite Films, 2009 University of Michigan - Ann Arbor
Fabrication And Optical Characterizations Of Smooth Silver-Silica Nanocomposite Films, Weiqiang Chen, Mark Thoreson, Alexander Kildishev, Vladimir Shalaev
We have studied the surface-smoothing effect of an ultrathin germanium (Ge) layer on silver (Ag)-silica (SiO2) nanocomposite films for superlensing applications. Our experimental results indicate that inserting a thin Ge layer below the silver-silica composite films can reduce the final surface root-mean-squared (RMS) roughness to under 1 nm. Additionally, the metal nanostructure plays a role in both the smoothing effect and the optical properties of the nanocomposite films. Our experimental results show that the Bruggeman effective medium theory (EMT) is not sufficiently accurate to describe some properties of our nanocomposite films. In addition to the constituent materials and their ...
On The Interaction Of An Eddy Current Coil With A Right-Angled Conductive Wedge, 2009 Iowa State University
On The Interaction Of An Eddy Current Coil With A Right-Angled Conductive Wedge, John R. Bowler, Theodoros Theodoulidis
John R. Bowler
A fundamental problem in eddy-current nondestructive evaluation is one of finding the quasi-static electromagnetic field of a cylindrical coil in the vicinity of the edge of a metal block. Although the field can be calculated numerically, an effective analytical approach can potentially provide a better understanding of the edge fields and form the basis of a procedure for solving a whole class of related edge problems including edge structures that contain corner cracks. One can represent the metal block as a conductive quarter space in an unbounded region. However, it has been found that the analysis is more straightforward if ...
Resistivity Recovery In Gd5si2.09ge1.91 By Annealing, 2009 Cardiff University
Resistivity Recovery In Gd5si2.09ge1.91 By Annealing, Ravi L. Hadimani, David C. Jiles
Ravi L Hadimani
Irreversible change in resistivity occurs in Gd5(SixGe1−x)4 (with 0.41