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Full-Text Articles in Physical Sciences and Mathematics
Investigation Of The Reflective Properties Of A Left-Handed Metamaterial, Amanda Durham
Investigation Of The Reflective Properties Of A Left-Handed Metamaterial, Amanda Durham
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The purpose of this project is to investigate the reflective properties of a left-handed metamaterial (LHM) through the use of a finite element analysis software called FEMLAB. In the 1960's, V. Veselago theorized that a material with negative permeability and negative permittivity has a negative index of refraction. In 2000, such a metamaterial was built and demonstrated at microwave frequencies. Previous work had focused on the transmission properties of the metamaterial. In our work, the reflected wave was examined for a LHM subject to an incident transverse electric wave. The different generalizations, first proposed by Veselago, of the Fresnel and …
Fabrication And Study Of Zno Micro- And Nanostructures, Monica Morales-Masis
Fabrication And Study Of Zno Micro- And Nanostructures, Monica Morales-Masis
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ZnO micro-structures and nano-structures have been grown on two types of substrate by reacting condensed Zn vapor with oxygen. The source material was either pure zinc powder or zinc acetate which was either evaporated or decomposed. This was done in the temperature range 500 C to 650 C, in a flowing Ar plus oxygen ambient at atmospheric pressure. Variations in the carrier gas composition, gas flow rate and the position of the substrate in the furnace were found to control the formation and the morphology of the nanostructures. Scanning electron microscopy images of samples grown from a Zn powder source …
Evanescent Microwave Characterization Of Carbon Nanotube Films Grown On Silicon Carbide Substrate, Kineshma Munbodh
Evanescent Microwave Characterization Of Carbon Nanotube Films Grown On Silicon Carbide Substrate, Kineshma Munbodh
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The electromagnetic characterization of carbon nanotube films (CNT) grown by the surface decomposition of silicon carbide (SiC) has been performed. The CNT films formed on the carbon and silicon terminated face of the SiC substrate were uncapped by an annealing process at a temperature of 4000 C with dwelling time up to 60 minutes in oxygen or carbon dioxide atmosphere. X-Y scans of the quality factor were used to deduce the local conductive properties of the films measured by evanescent microwave microscopy. Real and imaginary permittivity values, as determined by these electromagnetic measurements, provided valuable information for future field emission …
Comparative Investigation Of Dosimetric Tools In Imrt, Aaron Nicholas Garcia
Comparative Investigation Of Dosimetric Tools In Imrt, Aaron Nicholas Garcia
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Verification of the isodose distribution delivered to the planned tumor volume is required for quality assurance in the clinic. Verification in this context means ensuring that the actual dose delivered to a volume matches the dose that a computerized planning system intended that volume to receive. The computerized planning is performed by a Computerized Medical Systems (CMS) Intensity Modulated Radiation Therapy (IMRT) plan. Two methods of measuring the delivered dose are film dosimetry and diode dosimetry. This project will compare the relative isodose distribution profiles of film dosimetry and MapCheck (Sun Nuclear Corporation, a diode-based dosimetry system) to the relative …
Fabrication Of Silver Nanoparticles By Solution Phase Method And Physical Characterization Of Their Arrays, Jaesung Oh
Fabrication Of Silver Nanoparticles By Solution Phase Method And Physical Characterization Of Their Arrays, Jaesung Oh
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Synthesis of silver nanostructures has been an active research area for many decades because of their importance in biological sensing, imaging, electronics, optoelectronics and catalysis. In particular, much effort has been devoted to the controlled synthesis of silver nanowires because of their potential use as interconnects or active components in fabricating nanoscale devices. The solution phase method is used here to form Ag nanoparticles by reducing silver nitrate with ethylene glycol heated to 160°C. The additional presence of polyvinyl pyrrolidone plays a role of stabilizer to prevent an agglomeration and/or a capping agent to produce highly anisotropic nanowires. Silver nanoparticles …
Polarization Reversal In Potassium Titanyl Phosphate, William D. Mitchell
Polarization Reversal In Potassium Titanyl Phosphate, William D. Mitchell
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Polarization reversal in both hydrothermal and flux grown potassium titanyl phosphate was studied using square pulses at room temperature from 1600 V/mm to 5000 V/mm. Maximum switching current and inverse switching time data is compared to the ferroelectric polarization reversal model developed by Fatuzzo and Merz in the last century. Room temperature calculation of spontaneous polarization is reported and compared to that of potassium titanyl phosphate in the literature.