Effects of Dissipation on Propagation of Surface Electromagnetic and Acoustic Waves

Effects of Dissipation on Propagation of Surface Electromagnetic and Acoustic Waves

Date: May 2012
Creator: Nagaraj, Nagaraj
Description: With the recent emergence of the field of metamaterials, the study of subwavelength propagation of plane waves and the dissipation of their energy either in the form of Joule losses in the case of electomagnetic waves or in the form of viscous dissipation in the case of acoustic waves in different interfaced media assumes great importance. with this motivation, I have worked on problems in two different areas, viz., plasmonics and surface acoustics. the first part (chapters 2 & 3) of the dissertation deals with the emerging field of plasmonics. Researchers have come up with various designs in an efort to fabricate efficient plasmonic waveguides capable of guiding plasmonic signals. However, the inherent dissipation in the form of Joule losses limits efficient usage of surface plasmon signal. a dielectric-metal-¬dielectric planar structure is one of the most practical plasmonic structures that can serve as an efficient waveguide to guide electromagnetic waves along the metal-dielectric boundary. I present here a theoretical study of propagation of surface plasmons along a symmetric dielectric-metal-dielectric structure and show how proper orientation of the optical axis of the anisotropic substrate enhances the propagation length. an equation for propagation length is derived in a wide range of frequencies. ...
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Long-range surface plasmons in dielectric-metal-dielectric structure with highly anisotropic substrates

Long-range surface plasmons in dielectric-metal-dielectric structure with highly anisotropic substrates

Date: February 22, 2010
Creator: Nagaraj & Krokhin, Arkadii A.
Description: This article discusses long-range surface plasmons in dielectric-metal-dielectric structure with highly anisotropic substrates.
Contributing Partner: UNT College of Arts and Sciences
Guest Artist Recital: 2008-10-08 - The Mysore Brothers

Guest Artist Recital: 2008-10-08 - The Mysore Brothers

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Date: October 8, 2008
Creator: Mysore Nagaraj & Mysore Manjunath
Description: Guest artist recital presented at the UNT College of Music Recital Hall.
Contributing Partner: UNT Music Library
Evaluation of TBC-coated {beta}-NiAl substrates without a bond coat

Evaluation of TBC-coated {beta}-NiAl substrates without a bond coat

Date: April 1, 1996
Creator: Pint, B.A.; Nagaraj, B.A. & Rosenzweig, M.A.
Description: {beta}-NiAl substrates with various alloy additions and oxide dispersions were coated with Y{sub 2}O{sub 3}-stabilized ZrO{sub 2} using electron beam-physical vapor deposition. Cyclic oxidation experiments (1000-1200 C) were conducted to study effect of substrate dopants such as Y and Zr on coating lifetime without the intermediate metallic bond coat layer used in conventional thermal barrier coatings. Oxidation kinetics and Al{sub 2}O{sub 3} scale microstructures were compared to those for uncoated substrates. Degradation of substrate-alumina interface by void formation was the primary mechanism leading to coating spallation. Coating lifetime was correlated to alumina scale adhesion on unocated substrates.
Contributing Partner: UNT Libraries Government Documents Department
The effect of thermal aging on the thermal conductivity of plasma sprayed and EB-PVD thermal barrier coatings

The effect of thermal aging on the thermal conductivity of plasma sprayed and EB-PVD thermal barrier coatings

Date: May 1, 1996
Creator: Dinwiddie, R.B.; Beecher, S.C.; Porter, W.D. & Nagaraj, B.A.
Description: Thermal barrier coatings (TBCs) applied to the hot gas components of turbine engines lead to enhanced fuel efficiency and component reliability. Understanding the mechanisms which control the thermal transport behavior of the TBCs is of primary importance. Electron beam-physical vapor deposition (EV-PVD) and air plasma spraying (APS) are the two most commonly used coating techniques. These techniques produce coatings with unique microstructures which control their performance and stability. The density of the APS coatings was controlled by varying the spray parameters. The low density APS yttria-partially stabilized zirconia (yttria-PSZ) coatings yielded a thermal conductivity that is lower than both the high density APS coatings and the EB-PVD coatings. The thermal aging of both fully and partially stabilized zirconia are compared. The thermal conductivity of the coatings permanently increases upon exposure to high temperatures. These increases are attributed to microstructural changes within the coatings. This increase in thermal conductivity can be modeled using a relationship which depends on both the temperature and time of exposure. Although the EB-PVD coatings are less susceptible to thermal aging effects, results suggest that they typically have a higher thermal conductivity than APS coatings before thermal aging. The increases in thermal conductivity due to thermal aging ...
Contributing Partner: UNT Libraries Government Documents Department