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open access

Etching of Niobium Sample Placed on Superconducting Radio Frequency Cavity Surface in Ar/CL2 Plasma

Description: Plasma based surface modification is a promising alternative to wet etching of superconducting radio frequency (SRF) cavities. It has been proven with flat samples that the bulk Niobium (Nb) removal rate and the surface roughness after the plasma etchings are equal to or better than wet etching processes. To optimize the plasma parameters, we are using a single cell cavity with 20 sample holders symmetrically distributed over the cell. These holders serve the purpose of diagnostic ports for the… more
Date: September 1, 2011
Creator: Janardan Upadhyay, Larry Phillips, Anne-Marie Valente
Partner: UNT Libraries Government Documents Department
open access

SYNTHESIS AND CHARACTERIZATION OF SMART FUNCTIONAL COATINGS BY CHEMICAL SOLUTION DEPOSITION METHODS

Description: New coating technology enables the fabrication of low cost structural health monitoring (SHM) and tamper indication devices that can be employed to strengthen national and international safeguards objectives. In particular, such innovations could serve the safeguards community by improving both the timeliness of detection and confidence in verification and monitoring. This work investigates the synthesis of functional surface coatings using chemical solutions deposition methods. Chemical soluti… more
Date: July 19, 2011
Creator: Mendez-Torres, A.
Partner: UNT Libraries Government Documents Department
open access

Seeing the magnetic monopole through the mirror of topological surface states

Description: Existence of the magnetic monopole is compatible with the fundamental laws of nature, however, this illusive particle has yet to be detected experimentally. In this work, we show that an electric charge near the topological surface state induces an image magnetic monopole charge due to the topological magneto-electric effect. The magnetic field generated by the image magnetic monopole can be experimentally measured, and the inverse square law of the field dependence can be determined quantitati… more
Date: March 25, 2010
Creator: Qi, Xiao-Liang; Li, Rundong; /Stanford U., Phys. Dept.; Zang, Jiadong; U., /Fudan; Zhang, Shou-Cheng et al.
Partner: UNT Libraries Government Documents Department
open access

Quantum Phase Extraction in Isospectral Electronic Nanostructures

Description: Quantum phase is not a direct observable and is usually determined by interferometric methods. We present a method to map complete electron wave functions, including internal quantum phase information, from measured single-state probability densities. We harness the mathematical discovery of drum-like manifolds bearing different shapes but identical resonances, and construct quantum isospectral nanostructures possessing matching electronic structure but divergent physical structure. Quantum mea… more
Date: April 28, 2010
Creator: Moon, Christopher
Partner: UNT Libraries Government Documents Department
open access

Topological Insulators at Room Temperature

Description: Topological insulators are new states of quantum matter with surface states protected by the time-reversal symmetry. In this work, we perform first-principle electronic structure calculations for Sb{sub 2}Te{sub 3}, Sb{sub 2}Se{sub 3}, Bi{sub 2}Te{sub 3} and Bi{sub 2}Se{sub 3} crystals. Our calculations predict that Sb{sub 2}Te{sub 3}, Bi{sub 2}T e{sub 3} and Bi{sub 2}Se{sub 3} are topological insulators, while Sb{sub 2}Se{sub 3} is not. In particular, Bi{sub 2}Se{sub 3} has a topologically non… more
Date: March 25, 2010
Creator: Zhang, Haijun; Liu, Chao-Xing; Qi, Xiao-Liang; Dai, Xi; Fang, Zhong & Zhang, Shou-Cheng
Partner: UNT Libraries Government Documents Department
open access

TASK 2.5.5 NATURAL EXPOSURE TESTING IN CALIFORNIA

Description: Airborne particulate matter that settles on a roof can either reflect or absorb incoming solar radiation, dependent on the chemical content and size of the particles. These light scattering and absorption processes occur within a few microns of the surface, and can affect the solar reflectance of the roof. Wilkes et al. (2000) tested 24 different roof coatings on a low-slope test stand and observed about a 25% decrease in the solar reflectance of white-coated and aluminum-coated surfaces as the… more
Date: March 1, 2010
Creator: Miller, William A; Cheng, Mengdawn; New, Joshua Ryan; Ronnen, Levinson; Akbari, Hashem & Berhahl, Paul
Partner: UNT Libraries Government Documents Department
open access

CesrTA Retarding Field Analyzer Modeling Results

Description: Retarding field analyzers (RFAs) provide an effective measure of the local electron cloud density and energy distribution. Proper interpretation of RFA data can yield information about the behavior of the cloud, as well as the surface properties of the instrumented vacuum chamber. However, due to the complex interaction of the cloud with the RFA itself, understanding these measurements can be nontrivial. This paper examines different methods for interpreting RFA data via cloud simulation progra… more
Date: May 23, 2010
Creator: Calvey, J. R.; Celata, C. M.; Crittenden, J. A.; Dugan, G. F.; Greenwald, S.; Leong, Z. et al.
Partner: UNT Libraries Government Documents Department
open access

ENHANCED SAFEGUARDS: THE ROLE OF SMART FUNCTIONAL COATINGS FOR TAMPER INDICATION

Description: This work investigates the synthesis of smart functional coatings (SFC) using chemical solution deposition methods. Chemical solution deposition methods have recently received attention in the materials research community due to several unique advantages that include low temperature processing, high homogeneity of final products, the ability to fabricate materials with controlled surface properties and pore structures, and the ease of dopant incorporation in controlled concentrations. The optic… more
Date: February 24, 2012
Creator: Mendez-Torres, A.; Martinez-Rodriguez, M.; Brinkman, K. & Krementz, D.
Partner: UNT Libraries Government Documents Department
open access

Computational Investigation of FeS2 Surfaces and Prediction of Effects of Sulfur Environment on Stabilities

Description: Density functional theory calculations were employed to investigate the (001), (210), (III), and (110) surfaces of, F~S2' The surface free ene:gies were calculated in equilibrium with a sulfur environment using firstpnnclples based thermodynamics approach. Surfaces that feature metal atoms in their outermost layer are predicted to be higher m energy. Wlthm the studied subset of (I x I) terminations, the stoichiometric (001) surface termmated by a layer of sulfur atoms is the most stable for sul… more
Date: January 1, 2010
Creator: Alfonso, D. R.
Partner: UNT Libraries Government Documents Department
open access

Visualization of Fuel Cell Water Transport and Performance Characterization under Freezing Conditions

Description: In this program, Rochester Institute of Technology (RIT), General Motors (GM) and Michigan Technological University (MTU) have focused on fundamental studies that address water transport, accumulation and mitigation processes in the gas diffusion layer and flow field channels of the bipolar plate. These studies have been conducted with a particular emphasis on understanding the key transport phenomena which control fuel cell operation under freezing conditions. Technical accomplishments are lis… more
Date: May 30, 2010
Creator: Kandlikar, Satish G.; Lu, Zijie; Rao, Navalgund; Sergi, Jacqueline; Rath, Cody; Mc Dade, Christopher et al.
Partner: UNT Libraries Government Documents Department
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