Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 30 for “"absorptance"”.
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Direct and quantitative broadband absorptance micro/nano spectroscopy using FTIR and bilayer cantilever probes
… described to directly measure the quantitative absorptance spectra of micro/nano-sized structures using Fourier Transform Spectroscopy (FTS). The measurement technique combines optomechanical cantilever probes with a modulated broadband light source from an interferometer for spectroscopic …
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Étude d'une méthode exacte de détermination de l'indice de réfraction complexe de matériaux d'absorptance arbitraire: la photoligométrie
… exact, afin de prendre en compte les matériaux d'absorptance arbitraire sur un substrat lui aussi d'absorptance arbitraire. Il importe de souligner que sauf nos propres contributions, ce formalisme n'existe pas dans la littérature scientifique. En effet et au meilleur de notre connaissance, …
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Detailed thermal analysis of a thin-shell, spherical radiometer in Earth orbit
… independent models of emittance, long wavelength absorptance; and solar absorptance. The emittance as a function of temperature was determined from the Davisson, and Weeks analytical expression. The long wavelength absorptance as a function of incident angle, wavelength, and temperature was …
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Solar energy collection using vee-grooved surfaces
… are developed for the so-called "apparent" absorptance of a V-groove cavity, as well as for the "effective" absorptance of a V-grooved surface. These concepts are formulated in closed form mathematical equations, which facilitate both the optimization of V-grooved surfaces and their …
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Genetic algorithm gradient ascent (GAGA) optimization of compact symmetry-breaking photonic crystals
… the nonreciprocity of infrared radiation absorptance/emittance in planar and compact designs. Two different mechanisms to enable nonreciprocal infrared absorbers/emitters are simulated and compared – anomalous Hall effect in Weyl semimetals 2 and electric-current-induced Fizeau drag in …
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Investigation and Characterization of the Optical, Thermal, and Adsorption Properties of Carbon Aerogels for CO2 Capture Applications
… to measure reflectance, transmittance, and absorptance across the solar and thermal-infrared ranges. Mid-wave infrared thermography under a xenon arc lamp (1 Sun irradiance) quantified transient heating and cooling. Dynamic breakthrough experiments with a 11% CO₂ / 89% N₂ mixture at 25 °C, …
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Direct laser sintering of stainless steel : thermal experiments and numerical modelling
… the thermal conductivity and laser energy absorptance of the SLS powder bed. Experiments take place in a range of representative situations. Two temperature measurement systems are used, requiring some custom-designed elements. Conductivity values in the range 0.07 to 0.25 W/(m. K) are …
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Vanadium Oxide Microbolometers with Patterned Gold Black or Plasmonic Resonant Absorbers
… oxide, which preserves gold black's near unity absorptance. This patterned gold black also survives the dry-etch removal of the sacrificial polyimide used to fabricate the air-bridge bolometers. Infrared responsivity is improved 70% for mid-wave IR and 22% for long-wave IR. The increase in the …
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Engineering the optical properties of subwavelength devices and materials
… constructed a numerical model that predicts the absorptance of our devices. We then fabricated SNSPDs with varying geometries and engineered a preprocessing-free proximity-effect correction technique to realize uniform linewidths. We then constructed an optical apparatus to measure the …
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Thermomechanical sensitivity of microcantilever in the mid-infrared spectral region
… upon the cantilever. Separately, spectral absorptance of the cantilever was measured using Fourier transform infrared (FT-IR) microscopy, which was compared with analytical models of radiation onto the cantilever and heat flow within the cantilever. The predictions of microcantilever …
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Direct and quantitative absorptive spectroscopy of nanowires
… sample with monochromatic light, the absolute absorptance spectrum of the nanowire was measured and shown to match well with theory. This spectroscopic technique can conceivably be used to measure even smaller samples, samples which cannot be characterized using conventional methods.
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Development of Solar Sensitive Thin Film for Water Splitting and Water Heating using Solar Concentrator
… the incident radiation simply increase the solar absorptance by multiple reflections. Long time thermal stability and corrosion resistance in hot water was also studied for the copper oxide film. The results revealed that the copper oxide was very stable and showed no changes in optical properties …
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Identification and Characterization of Shallow Impurity States in Gallium-Arsenide and Indium-Phosphide Using Photothermal Ionization Spectroscopy
… properties of reflectance, transmittance, and absorptance, and photoconductive response of high purity epitaxial GaAs films are predicted and compared with experimental photothermal ionization spectra. The model accounts for many of the peculiar features that are frequently observed in these …
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Identification and characterization of shallow impurity states in gallium arsenide and indium phosphide using photothermal ionization spectroscopy
… properties of reflectance, transmittance, and absorptance, and photoconductive response of high purity epitaxial GaAs films are predicted and compared with experimental photothermal ionization spectra. The model accounts for many of the peculiar features that are frequently observed in these …
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Laser Surface Texturing, Crystallization and Scribing of Thin Films in Solar Cell Applications
… the defect density. In addition, a comparison of absorptance spectra for various surface morphologies and crystallinity is developed and the absorptance across the solar spectrum shows that the combination of surface texturing and crystallization induced by laser processing is very promising for …
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Analysis of flat-plate solar collector durability test data
… important material properties include the solar absorptance and long wave emittance of the absorber surface, solar and long wave transmittance of the cover material and the thermal conductivity of the insulation. Tests were conducted by three independent testing laboratories located in Phoenix, …
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Characterization of gold black and its application in un-cooled infrared detectors
… different porosities. Interestingly, with aging, absorptance of the coatings improved, which is explained using conductivity form of Bergman Formulism. Underlying aim of this work was to utilize gold blacks to improve sensitivity in un-cooled IR sensors consist of pixel arrays. To achieve this, …
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Optical properties of black silicon - an analysis
… visible range of wavelengths. It exhibits high absorptance in the visible and infrared region. The main objective of this thesis is to study the various fabrication techniques used to form Black Silicon, present a comparative study of structural differences and analyze its optical properties by …
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Investigations on Multiscale Fractal-textured Superhydrophobic and Solar Selective Coatings
… with respect to their optical properties of absorptance, emittance, and figure of merit (FOM).
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Calcium vapour deposition on semiconducting polymers studied by adsorption calorimetry and visible light absorption
… calcium atom at low coverages. The change in absorptance at higher coverages correlates perfectly with the population of reacted Ca atoms determined calorimetrically. The size of the absorbance cross-section, and its position just within the band gap of the polymer, are consistent with the …
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