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 38 for “"Ray-trace"”.
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An Application of Wavelet Techniques to Bi-directionality in the Monte Carlo Ray Trace Environment
… of directionality into the Monte Carlo ray-trace (MCRT) environment: (1) the development of a methodology for using directional surface optical data, (2) the measurement of the bi-directional reflectivity functions for two different surfaces, and (3) MCRT simulations performed using …
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Uncertainty and Confidence Intervals of the Monte Carlo Ray-Trace Method in Radiation Heat Transfer
… transfer problems solved using the Monte Carlo ray-trace method (MCRT). Four equations are developed to predict the uncertainty of the distribution factor from one surface to another, the global uncertainty of all the distribution factors in an enclosure, the uncertainty of the net heat flux …
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Analysis of the Effect of the August 2017 Eclipse on the Ionosphere Using a Ray-trace Algorithm
The total solar eclipse over the continental United States on August 21, 2017 offered a unique opportunity to study the dependence of the ionospheric density and morphology on incident solar radiation. Unique responses may be witnessed during eclipses, including changes in radio frequency (RF) …
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A Monte Carlo ray trace tool for predicting contrast in naval scenes including the effects of polarization
… and nighttime conditions by specifying if the ray trace is in the infrared or visible light range. The location of the sun for daytime conditions, and the temperature of the surfaces for nighttime conditions, can all be adjusted by the user. In order to get an accurate estimation of the signal …
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Optical and Thermal Radiative Simulation of an Earth Radiation Budget Instrument
… The numerical model is based on the Monte Carlo Ray-Trace (MCRT) method. The major optical components of the instrument are incorporated into the ray-trace model using 3-D surface equations. A CAD model of the instrument baffle is imported directly into the ray-trace environment using an STL …
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SOFAR signal shaping : influence of topography and relative source depth
… (2) blocking and partial blocking of direct rays by seamounts and narrow undersea ridges and (3) a sound speed profile displaced downwards by a filament of warm surface water. Comparisons with ray trace and normal mode models show that some of the received signals consist of a combination of …
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Temperature, pressure, and infrared image survey of an axisymmetric heated exhaust plume
… image invokes the use of an inverse Monte-Carlo ray trace algorithm and an infrared band model for exhaust gases. This dissertation describes an experiment in which the above-mentioned field variables were carefully measured. Results from this experiment, namely tables of measured temperature and …
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The reprocessing and extended interpretation of seismic reflection data recorded over the Hayesville-Fries thrust sheet in southwestern North Carolina
… relative to profile direction. Initial shotpoint ray trace modeling shows the chaotic nature of raypaths and some of the problems associated with the imaging of reflections when complex geology is involved. Data reprocessing and two-dimensional ray trace modeling yield results which suggest that …
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Advances in Radiation Heat Transfer and Applied Optics, Including Application of Machine Learning
… reducing the required resources. The Monte Carlo ray-trace (MCRT) method is the state-of-the-art approach for modeling radiation heat transfer. It has the disadvantage of being a complex and computationally expensive process. In this dissertation, after first identifying the uncertainties …
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A parametric study of the radiative and optical characteristics of a scanning radiometer for Earth Radiation Budget applications using the Monte-Carlo method
… of these instruments. The Monte-Carlo ray-trace method has been applied to the ERBE and CERES scanning radiometer instruments to calculate radiation exchange. In a radiative analysis, the surfaces of both instruments are found to emit a significant amount of radiation to the detector. …
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Optical Analysis of a Linear-Array Thermal Radiation Detector for Geostationary Earth Radiation Budget Applications
… detector consists of a thermopile linear array thermal radiation detector. The principal objective of this research is to develop an optical model for the detector and its cavity. The model based on the Monte-Carlo ray-trace (MCRT) method, permits parametric studies to optimize the design of …
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Acceleration techniques for the radiative analysis of general computational fluid dynamics solutions using reverse Monte-Carlo ray tracing
A reverse Monte-Carlo ray trace capable of performing a radiative analysis on arbitrary multiple overlapping structured computational fluid dynamics solution sets is developed. In order to make effective use of time, a method based on a set of simplifying assumptions but using the same calculation …
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Design and analysis of radiometric instruments using high-level numerical models and genetic algorithms
… modeling environment consists of a Monte Carlo ray-trace (MCRT) model of the optical system coupled to a transient, three-dimensional finite-difference electrothermal model of the detector assembly with an analytic model of the signal-conditioning circuitry. The environment provides a complete …
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Creation and Experimental Validation of a Numerical Model of a Michelson Interferometer
… of an optical instrument using the Monte-Carlo ray-trace (MCRT) method has been shown to be an efficient method for transferring knowledge of the coherence state of a beam of light from one instrument to another. The goal of the effort reported here is to create and experimentally validate an …
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Real time bottom reverberation simulation in deep and shallow ocean environments
… simulations of the ocean environment. Using the ray tracing code, BELLHOP, the Mission Oriented Operating Suite (MOOS), methods outlined by the Naval Research Laboratory (NRL) for bottom reverberation, and MATLAB, a model will be developed to incorporate the effects of bottom reverberation into …
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Real time bottom reverberation simulation in deep and shallow ocean environments
… simulations of the ocean environment. Using the ray tracing code, BELLHOP, the Mission Oriented Operating Suite (MOOS), methods outlined by the Naval Research Laboratory (NRL) for bottom reverberation, and MATLAB, a model will be developed to incorporate the effects of bottom reverberation into …
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A Monte-Carlo-based simulation of jet exhaust nozzle thermal radiative signatures
… of the model is a highly flexible Monte-Carlo ray-trace formulation which is capable of simulating real surface behavior, such as specular reflections, and allows for variation of input parameters such as temperature, surface properties, and geometry. For given input parameters, the model …
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A new simplified vector-based model to support solar energy planning at urban scale
… (1) Current advanced simulation models based on ray trace and ray interception techniques are not effectively scalable to evaluate solar potential at urban scale due to the expensive modelling process and computational cost. (2) Simple and statistical models developed for large-scale analysis are …
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GHOST IMAGE ANALYSIS FOR OPTICAL SYSTEMS
… For each possible ghost layout, paraxial ray tracing is performed to calculate the locations of the Gaussian cardinal points, the locations and diameters of the ghost entrance and exit pupils, the locations and diameters of the ghost entrance and exit windows, and the ghost chief and …
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Second-Surface Mirror Effects in Thin-Film Absorber Layers
… model that is derived using the Monte Carlo ray-trace (MCRT) method. These models are compared by using them to predict the transient temperature response of a generic thermal radiation detector. Results are presented for absorber layers in which the index of refraction is equal to the …
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