529 research outputs found
Optical Coherence Tomography guided Laser-Cochleostomy
Despite the high precision of laser, it remains challenging to control the laser-bone ablation without injuring the underlying critical structures. Providing an axial resolution on micrometre scale, OCT is a promising candidate for imaging microstructures beneath the bone surface and monitoring the ablation process. In this work, a bridge connecting these two technologies is established. A closed-loop control of laser-bone ablation under the monitoring with OCT has been successfully realised
Efektivnà a expresivnà mikrofasetové modely
Název: EfektivnĂ a expresivnĂ mikrofasetovĂ© modely Autor: Asen Atanasov Katedra: Katedra softwaru a vĂ˝uky informatiky VedoucĂ: doc. Dr. Alexander Wilkie, Katedra softwaru a vĂ˝uky informatiky Abstrakt: V realistickĂ©m modelovánĂ vzhledu jsou drsnĂ© povrchy, kterĂ© majĂ mikroskopickĂ© detaily, popsány pomocĂ tzv. mikrofazetovĂ˝ch modelĹŻ. Mezi tyto modely patřà analytickĂ© modely, kterĂ© statisticky definujĂ fyzikálnÄ› zaloĹľenĂ˝ mikropovrch. TakovĂ© modely jsou široce pouĹľĂvány v praxi, protoĹľe jsou nenároÄŤnĂ© na vĂ˝poÄŤet a nabĂzejĂ znaÄŤnou flexibilitu ve vzhledu, kterĂ˝ s nimi lze docĂlit. Tyto modely mohou bĂ˝t rozšĂĹ™enĂ© o viditelnĂ© povrchovĂ© prvky prostĹ™ednictvĂm normálovĂ© mapy. Stále však existujĂ oblasti, ve kterĂ˝ch lze tento obecnĂ˝ typ modelu vylepšit: dĹŻleĹľitĂ© funkce, jako je Ĺ™ĂzenĂ anizotropie, nÄ›kdy postrádajĂ analytická Ĺ™ešenĂ a účinnĂ© vykreslovánĂ normálovĂ˝ch map vyĹľaduje pĹ™esnĂ© a obecnĂ© filtrovacĂ algoritmy. Posunujeme pĹ™edchozĂ práci v následujĂcĂch oblastech: odvodĂme analytickĂ© anizotropnĂ modely, pĹ™eformulujeme problĂ©m filtrovánĂ a navrhneme efektivnĂ filtraÄŤnĂ algoritmus zaloĹľenĂ˝ na novĂ© datovĂ© struktuĹ™e filtraÄŤnĂch dat. KonkrĂ©tnÄ› odvodĂme obecnĂ˝ vĂ˝sledek v mikrofazetovĂ© teorii: na základÄ› libovolnĂ©ho mikropovrchu definovanĂ©ho pomocĂ standardnĂ mikrofazetovĂ© statistiky ukážeme, jak konstruovat statistiku...Title: Efficient and Expressive Microfacet Models Author: Asen Atanasov Department: Department of Software and Computer Science Education Supervisor: doc. Dr. Alexander Wilkie, Department of Software and Computer Science Education Abstract: In realistic appearance modeling, rough surfaces that have micro- scopic details are described using so-called microfacet models. These include analytical models that statistically define a physically-based microsurface. Such models are extensively used in practice because they are inexpensive to compute and offer considerable flexibility in terms of appearance control. Also, small but visible surface features can easily be added to them through the use of a normal map. However, there are still areas in which this general type of model can be improved: important features like anisotropy control sometimes lack analytic solutions, and the efficient rendering of normal maps requires accurate and general filtering algorithms. We advance the state of the art with regard to such models in these areas: we derive analytic anisotropic models, reformulate the filtering problem and propose an efficient filtering algorithm based on a novel filtering data structure. Specifically, we derive a general result in microfacet theory: given an arbitrary microsurface defined via standard...Katedra softwaru a vĂ˝uky informatikyDepartment of Software and Computer Science EducationMatematicko-fyzikálnĂ fakultaFaculty of Mathematics and Physic
Ray Tracing Gems
This book is a must-have for anyone serious about rendering in real time. With the announcement of new ray tracing APIs and hardware to support them, developers can easily create real-time applications with ray tracing as a core component. As ray tracing on the GPU becomes faster, it will play a more central role in real-time rendering. Ray Tracing Gems provides key building blocks for developers of games, architectural applications, visualizations, and more. Experts in rendering share their knowledge by explaining everything from nitty-gritty techniques that will improve any ray tracer to mastery of the new capabilities of current and future hardware. What you'll learn: The latest ray tracing techniques for developing real-time applications in multiple domains Guidance, advice, and best practices for rendering applications with Microsoft DirectX Raytracing (DXR) How to implement high-performance graphics for interactive visualizations, games, simulations, and more Who this book is for: Developers who are looking to leverage the latest APIs and GPU technology for real-time rendering and ray tracing Students looking to learn about best practices in these areas Enthusiasts who want to understand and experiment with their new GPU
Modeling thermal phenomena and searching for new thermally induced monitor signals in large sale gravitational wave detectors
The Laser Interferometer Gravitational-wave Observatory (LIGO) array’s 4 km detectors have transitioned from an initial configuration (iLIGO) to an enhanced configuration (eLIGO) [1]. Both configurations relied on high circulating laser powers to achieve sensitivity goals between 150 Hz and 8 kHz. These power levels were sufficient to induce thermally driven focal affects in the primary optics. Since the detectors were designed to achieve maximum sensitivity when laser light was optimally coupled (mode matched) into the antenna, small deviations in focal parameters influenced performance. A laser based thermal compensation system (TCS) was installed for use in both configurations to counteract excessive or insufficient thermal lensing. Consequently a toy model has been studied to search for detector derived parameters that might be used to monitor the focal state of the two most affected optics. Additional thermal behaviors induced by the TCS were investigated and modeled
Modeling Atmosphere-Ocean Radiative Transfer: A PACE Mission Perspective
The research frontiers of radiative transfer (RT) in coupled atmosphere-ocean systems are explored to enable new science and specifically to support the upcoming Plankton, Aerosol, Cloud ocean Ecosystem (PACE) satellite mission. Given (i) the multitude of atmospheric and oceanic constituents at any given moment that each exhibits a large variety of physical and chemical properties and (ii) the diversity of light-matter interactions (scattering, absorption, and emission), tackling all outstanding RT aspects related to interpreting and/or simulating light reflected by atmosphere-ocean systems becomes impossible. Instead, we focus on both theoretical and experimental studies of RT topics important to the science threshold and goal questions of the PACE mission and the measurement capabilities of its instruments. We differentiate between (a) forward (FWD) RT studies that focus mainly on sensitivity to influencing variables and/or simulating data sets, and (b) inverse (INV) RT studies that also involve the retrieval of atmosphere and ocean parameters. Our topics cover (1) the ocean (i.e., water body): absorption and elastic/inelastic scattering by pure water (FWD RT) and models for scattering and absorption by particulates (FWD RT and INV RT); (2) the air-water interface: variations in ocean surface refractive index (INV RT) and in whitecap reflectance (INV RT); (3) the atmosphere: polarimetric and/or hyperspectral remote sensing of aerosols (INV RT) and of gases (FWD RT); and (4) atmosphere-ocean systems: benchmark comparisons, impact of the Earth's sphericity and adjacency effects on space-borne observations, and scattering in the ultraviolet regime (FWD RT). We provide for each topic a summary of past relevant (heritage) work, followed by a discussion (for unresolved questions) and RT updates
The characteristics and feasibility of an in-line debris control technique for KrF excimer laser ablative micromachining
To observe KrF excimer laser ablation through thin liquid film of de-ionized (DI) water and the
effects thereof on debris control, equipment was designed to contain a small control volume that could
be supplied with a fixed flow velocity thin film of DI water to immerse a bisphenol A polycarbonate
workpiece. Using the same equipment comparison with ablation in ambient air was possible.
The positional debris deposition of samples machined in ambient air was found to show
modal tendency reliant on the feature shape machined and according to species size. This is proposed
to be due to the interaction of multiple shockwaves at the extent of ablation plumes generated at
geometry specific locations in the feature. Debris was deposited where the shockwaves collide.
Ablating under a flowing thin film of DI water showed potential to modify the end position and
typical size of the debris produced, as well as increased homogeneity of deposition density. Compared
with a sample machined in ambient air, the use of immersion has reduced the range of debris
deposition by 17% and the deposition within the boundary of the ablation plume has a comparatively
even population density. Unlike samples machined in ambient air, outside the ablation plume extents
positional control of deposited debris by thin film flowing DI water immersion was evidenced by
rippled flow line patterns, indicating the action of transport by fluid flow. A typical increase in debris
size by an order of magnitude when using DI water as an immersing liquid was measured, a result that
is in line with a colloidal interaction response... cont'd
Modeling atmosphere-ocean radiative transfer: A PACE mission perspective
The research frontiers of radiative transfer (RT) in coupled atmosphere-ocean systems are explored to enable new science and specifically to support the upcoming Plankton, Aerosol, Cloud ocean Ecosystem (PACE) satellite mission. Given (i) the multitude of atmospheric and oceanic constituents at any given moment that each exhibits a large variety of physical and chemical properties and (ii) the diversity of light-matter interactions (scattering, absorption, and emission), tackling all outstanding RT aspects related to interpreting and/or simulating light reflected by atmosphere-ocean systems becomes impossible. Instead, we focus on both theoretical and experimental studies of RT topics important to the science threshold and goal questions of the PACE mission and the measurement capabilities of its instruments. We differentiate between (a) forward (FWD) RT studies that focus mainly on sensitivity to influencing variables and/or simulating data sets, and (b) inverse (INV) RT studies that also involve the retrieval of atmosphere and ocean parameters. Our topics cover (1) the ocean (i.e., water body): absorption and elastic/inelastic scattering by pure water (FWD RT) and models for scattering and absorption by particulates (FWD RT and INV RT); (2) the air-water interface: variations in ocean surface refractive index (INV RT) and in whitecap reflectance (INV RT); (3) the atmosphere: polarimetric and/or hyperspectral remote sensing of aerosols (INV RT) and of gases (FWD RT); and (4) atmosphere-ocean systems: benchmark comparisons, impact of the Earth’s sphericity and adjacency effects on space-borne observations, and scattering in the ultraviolet regime (FWD RT). We provide for each topic a summary of past relevant (heritage) work, followed by a discussion (for unresolved questions) and RT updates
Modeling Atmosphere-Ocean Radiative Transfer: A PACE Mission Perspective
The research frontiers of radiative transfer (RT) in coupled atmosphere-ocean systems are explored to enable new science and specifically to support the upcoming Plankton, Aerosol, Cloud ocean Ecosystem (PACE) satellite mission. Given (i) the multitude of atmospheric and oceanic constituents at any given moment that each exhibits a large variety of physical and chemical properties and (ii) the diversity of light-matter interactions (scattering, absorption, and emission), tackling all outstanding RT aspects related to interpreting and/or simulating light reflected by atmosphere-ocean systems becomes impossible. Instead, we focus on both theoretical and experimental studies of RT topics important to the science threshold and goal questions of the PACE mission and the measurement capabilities of its instruments. We differentiate between (a) forward (FWD) RT studies that focus mainly on sensitivity to influencing variables and/or simulating data sets, and (b) inverse (INV) RT studies that also involve the retrieval of atmosphere and ocean parameters. Our topics cover (1) the ocean (i.e., water body): absorption and elastic/inelastic scattering by pure water (FWD RT) and models for scattering and absorption by particulates (FWD RT and INV RT); (2) the air-water interface: variations in ocean surface refractive index (INV RT) and in whitecap reflectance (INV RT); (3) the atmosphere: polarimetric and/or hyperspectral remote sensing of aerosols (INV RT) and of gases (FWD RT); and (4) atmosphere-ocean systems: benchmark comparisons, impact of the Earth’s sphericity and adjacency effects on space-borne observations, and scattering in the ultraviolet regime (FWD RT). We provide for each topic a summary of past relevant (heritage) work, followed by a discussion (for unresolved questions) and RT updates
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