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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
151

Texture Synthesis for Surface Inspection

Bosnar, Lovro, Rauhut, Markus, Hagen, Hans, Gospodnetic, Petra 07 July 2022 (has links)
The automated visual surface inspection planning is an important part of the quality assurance in automated custom product manufacturing. Visual surface inspection planning tackles image acquisition design and defect detection. Both tasks greatly benefit from the utilization of realistic and automated image synthesis of the inspected object. The realism of synthesized images greatly depends on object material, whose properties are largely influenced by texture. In this work, we focus on parametric texture synthesis and its application for visual surface inspection planning. We start by analyzing texture present on physical samples and introduce the requirements for texture synthesis models in visual surface inspection. Based on observation and surface characterization standards we present a model capable of reproducing texture on physical samples. This approach is generalized and further models are presented with respect to requirements. Finally, we highlight the importance of surface texture from the visual inspection planning perspective.
152

Performance Loss Rate and Temperature Modeling in Predictive Energy Yield Programs for Utility-Scale Solar Power Plants

Dinius, Katelynn M 01 December 2021 (has links) (PDF)
The Gold Tree Solar Farm, designed by REC Solar, has a rated output power of 4.5 MW and began operation in 2018 to provide electricity to Cal Poly’s campus. Gold Tree Solar Farm site terrain consists of rolling hills and uneven slopes. The uneven typography results in interrow shading, requiring a modified tracking control algorithm to maximize power production. Predicting a utility solar field’s lifetime energy yield is a critical step in assessing project feasibility and calculating project revenue. The MATLAB-based predictive power model developed for this field overpredicted power in the middle of the day. The purpose of this thesis was to develop a point-in-time power routine to run through experimental data collected from the Gold Tree Solar Farm and compare different cell temperature and degradation models in an effort to correct this overprediction. Increasing cell temperature reduces power output of a solar panel, and an objective of this analysis was to find a model that accurately predicted cell temperature to calculate this loss. Seven cell temperature models were adjusted to fit the specifications of the Gold Tree Solar Farm and compared to thermocouple measurements from the field. Frequent partial shading, which results in thermal cycling, contributes to accelerated module degradation and power loss. Yearly and seasonal plant degradation rates driven by environmental factors such as temperature, UV radiation, and relative humidity were calculated and integrated into the predictive power model.
153

Fusing Shape-from-shading with Stereo

Strunc, Joesef January 2011 (has links)
The thesis deals with incorporating the shape-from-shading technique into the multi-view stereo (MVS) reconstruction framework using the Oren-Nayar reflectance model for rough natural materials. Two methods for enhancing the MVS algorithm with new photo-consistency measure are proposed. Experiments with the laboratory images as well as with images of Mars's surface were conducted, proving that the proposed plane-sweeping method using shading information suitable for combining with MVS can nd the correct position of surface in 3D scene. The experiments also showed, that the Oren-Nayar reflectance model is very accurate for some real-world materials and it can be succesfuly used in the plane-sweeping method to accomplish better results than the Lambert's reflectance model. With precisely estimated material parameters and the light source and camera directions, it is possible to achieve the accuracy of few centimeters in estimating the position of real surface in the scene. / <p>Validerat; 20110825 (anonymous)</p>
154

Glare, Daylight and View:“Exploratory study of the effect of patterns on glare and view in an indoor environment.”

Nazari, Marzieh January 2019 (has links)
The dilemma of keeping the daylight quality and view to the outside or protecting our eyes from disturbing glare by covering the window is a moment that probably everyone has experienced in their life. Having access to daylight and enjoying the view to the outside when there is not visual comfort has been a problematic issue related to the window in space. Shading devices are designed in different shapes and forms to control glare and also energy consumption inside the space. Using shading covers part of the window and it affects the light quality and view to the outside and can change our perception from architectural space.In this thesis, the main question is how can we protect the indoor space from discomfort glare without covering the whole part of the window by curtain, blinds or shading devices in order to keep daylight quality and view to the outside.Glare is a phenomenon that is related to the viewpoint of observers and in order to study the glare metrics, the data from 140 viewpoints of the observer in 20 different locations in one simulated room were analyzed based on three main factors:1- Glare Metrics2- Light Quality3- ViewThe 20 selected patterns were simulated in [Rhino /Grasshopper/ Diva] software to analyze the glare and daylight metrics in Solstices and Equinoxes. Also, in order to define a parameter for view, one questionnaire was used and the responses from 40 participants were collected and all of the data were evaluated by mathematics and statistics methods.The final aim of the study is to introduce some simple principles for patterns of shadings to provide better-daylit environment and view to the outside with most visual comfort conditions for the user inside the space.
155

Assessing Wake Shading Effects in Wind Farms : Impact of turbine spacing and yaw angle

Tesfaye, Dawit Kefyalew January 2024 (has links)
This study investigates the wake shading effect in wind farms, focusing on turbine spacing, horizontal rotor tilt (yaw angle), wind speed, and power production. With the global population increasing, the demand for energy continues to rise, emphasizing the importance of renewable energy sources like wind power. In wind farms, where multiple turbines operate together, the wake effect resulting from one turbine's influence on wind flow for others significantly impacts their power production. This research is focused around Jädraås Wind Power Park in Sweden, using a scaled model of a section of this park in a controlled environment to conduct a detailed analysis. Utilizing both experimental setups in a wind tunnel and numerical simulations for visualization, the study explores the dynamics of wake interactions among turbines and proposes to mitigate their adverse effects.Through the experiments conducted in the wind tunnel, the results demonstrate significant wakeinduced power losses at downstream turbines. The yaw adjustment mechanism of the upstream turbine is used so as to see how it has affected the power output of downstream turbine. The results also indicate significant reductions in power production as a function of turbine spacing. Specifically, the maximum reduction in power output, influenced by the presence of two upstream turbines, occurred at closer spacings between them: a decrease of 66% at 2.08D (2.08 Rotor Diameters between the downstream and the nearest upstream turbine) and 45% at 4.15D. Conversely, at broader spacings of 7.29D and 8.3D, the reductions were more moderate, a decrease of 28% and 18%, respectively. These findings underscore the critical influence of spatial arrangement on the wake-induced power losses within wind farms.Through an investigation of two purposely positioned upstream and downstream turbines at 4D meter of spacing, the optimal yaw angle for maximum combined power generation has been predicted using sinusoidal fitting, the results indicated that at yaw angle range of ±11° of theupstream turbine rotor, a maximum combined power output has been observed. Hence, a sophisticated optimization mechanism should be employed in an operating wind farm so as tolower wake effects.
156

Capturing Key Knowledge Exchanges within the Design Process of Transformable Shading Systems

Kalantar Mehrjardi, Negar 01 July 2016 (has links)
In the field of sustainable architecture, transformability is an important way of actively responding to ambient conditions while also meeting the needs of occupants and addressing issues of building performance. This research contributes knowledge for architects about the potential of kinetics for the shading system to respond effectively to changes in its environment. Within contemporary architecture, there is a growing interest in motion; buildings and their parts are gradually shifting from static to dynamic. However, contemporary activities in architecture are evidence of a lack of a holistic approach to the design of motion in architecture and the design of motion as an alternative mode of design thinking is still in its infancy. Consequently, the existing tradition of static forms being the sole forms taught in architectural studies should be reevaluated as a design strategy. This research is a step in the direction of better understanding the key knowledge exchanges within the design process of transformable shading systems. It will seek to investigate, explore, and propose how the concept of transformability in designing shading systems can be suggested, depicted, or physically incorporated in building envelopes. In order to get the full potential of the design process of transformable shading systems, this study presents a design workflow of a specific case, called AURA, that helps to create openings for establishing a proper design methodology of transformable shading systems. While the workflow will be concerned with identifying the key decision nodes, it is anticipated that in-depth development will determine critical parameters addressing transformation itself as a design parameter of transformable shading systems. Two studio-based courses offered at Virginia Tech and Texas AandM by the author will become a testing ground for evaluating the key decision nodes found in the design process of AURA within the context of architectural programs, bringing forth the opportunity to expand the current domain of transformable shading systems to a broader perspective of architecture pedagogy. In this case, this research is a step towards adding values directly into the content of the curricula, and thus into the field of design education as a whole.' / Ph. D.
157

Modélisation 3D à partir d'images : contributions en reconstruction photométrique à l'aide de maillages déformables / Multi-view Shape Modeling from Images : Contributions to Photometric-based Reconstruction using Deformable Meshes

Delaunoy, Amaël 02 December 2011 (has links)
Comprendre, analyser et modéliser l'environment 3D à partir d'images provenant de caméras et d'appareils photos est l'un des défis majeurs actuel de recherche en vision par ordinateur. Cette thèse s'interesse à plusieurs aspects géométriques et photometriques liés à la reconstruction de surface à partir de plusieurs caméras calibrées. La reconstruction 3D est vue comme un problème de rendu inverse, et vise à minimiser une fonctionnelle d'énergie afin d'optimiser un maillage triangulaire représentant la surface à reconstruire. L'énergie est définie via un modèle génératif faisant naturellement apparaître des attributs tels que la visibilité ou la photométrie. Ainsi, l'approche présentée peut indifférement s'adapter à divers cas d'application tels que la stéréovision multi-vues, la stéréo photométrique multi-vues ou encore le “shape from shading” multi-vues. Plusieurs approches sont proposées afin de résoudre les problèmes de correspondances de l'apparence pour des scènes non Lambertiennes, dont l'apparence varie en fonction du point de vue. La segmentation, la stéréo photométrique ou encore la réciprocité d'Helmholtz sont des éléments étudiés afin de contraindre la reconstruction. L'exploitation de ces contraintes dans le cadre de reconstruction multi-vues permet de reconstruire des modèles complets 3D avec une meilleure qualité. / Understanding, analyzing and modeling the 3D world from 2D pictures and videos is probably one of the most exciting and challenging problem of computer vision. In this thesis, we address several geometric and photometric aspects to 3D surface reconstruction from multi-view calibrated images. We first formulate multi-view shape reconstruction as an inverse rendering problem. Using generative models, we formulate the problem as an energy minimization method that leads to the non-linear surface optimization of a deformable mesh. A particular attention is addressed to the computation of the discrete gradient flow, which leads to coherent vertices displacements. We particularly focus on models and energy functionals that depend on visibility and photometry. The same framework can then be equally used to perform multi-view stereo, multi-view shape from shading or multi-view photometric stereo. Then, we propose to exploit different additional information to constraint the problem in the non-Lambertian case, where the appearance of the scene depends on the view-point direction. Segmentation for instance can be used to segment surface regions sharing similar appearance or reflectance. Helmholtz reciprocity can also be applied to reconstruct 3D shapes of objects of any arbitrary reflectance properties. By taking multiple image-light pairs around an object, multi-view Helmholtz stereo can be performed. Using this constrained acquisition scenario and our deformable mesh framework, it is possible to reconstruct high quality 3D models.
158

Tvorba mikroklimatu průmyslové haly s vysokými nároky na jeho rovnoměrnost / Creating a microclimate of an industrial building with high demands on its uniformity

Tůmová, Eliška January 2015 (has links)
This diploma thesis deals with the optimization of microclimate of an industrial building. There is required constant temperature with minimal fluctuations during manufacturing process in the building. Due to insufficient cooling power of air-conditioning system was objective to design a solution that ensures stability of internal temperature during production especially in summer and simultaneously should be the solution economically acceptable. Simulation shows original state defined problems. Some new or unusual materials for solar shading are reviewed in the thesis by the experimental measurements and by the comparative method. To each material is assigned shading coefficient according to Czech standards, thereby is achieved universality for calculations of heat gains resulting from solar radiation. By one part of the experiments and their evaluation is determined thickness of the standard single glass glazing. It is also determined proportional transmittance of solar radiation for certain multiwall polycarbonates, which are currently used as fillers of industrial skylights and production hall‘s window openings. From experiments resulting design is subjected to the simulation. Comparison of temperatures is shown for the time before the installation of designed solar shading and after the installation of the solar shading.
159

Deferred Shading / Deferred Shading

Starý, Petr January 2009 (has links)
Work deals with design and implementation a tutorial for demonstration deferred shading technique and its possibilities. It explains lighting and shading principles in intuitive and interactive way. Deferred shading is a technique which determines pixel color after the geometry rasterization of the entire scene. In other words the processing of geometry does not interfere with the shading process.
160

Monteringshöjd och markinterferens i nordliga solkraftsparker : Minskade skuggningseffekter från ansamling av snö i markmonterade solcellsanläggningar i norra Sverige.

Edebo, Gabriella January 2023 (has links)
Markmonterade solcellsanläggningar i norra Sverige behöver ta hänsyn till förekomsten av snö och risken för markinterferens, vilket innebär att snömängden i framkant av panelerna gör att den snö som ackumuleras ovanpå inte kan glida av. Följden blir skuggning av panelerna som därmed får nedsatt eller helt utebliven elproduktion. Syftet med arbetet var att besvara frågeställningar kring vilken montagehöjd som krävs för att undvika problemet samt om den ökade engångskostnaden kompenseras av potentialen till ökad produktion under vintermånaderna. Metoden bestod främst av att jämföra produktionsdata från en solpark i Östersund med värden för solinstrålning och snödjup från SMHI för att avgöra vilken effekt snöskuggning haft på produktionen och hur utfallet skulle ha sett ut vid olika monteringshöjder av anläggningen. Resultaten visar att det finns stor potential till goda produktionsvärden under vårvintern, förutsatt att markinterferens inte finns närvarande. Anledningen beror troligtvis på högt albedo från snötäckt mark och lägre lufttemperaturer vilket har en positiv inverkan på modulernas verkningsgrad. En beräkningsmodell utvecklades för att uppskatta en lämplig monteringshöjd för en solpark utifrån dess tänkta utformning och det förväntade snödjupet på platsen. Förhoppningen är att modellen kan bidra till ökad kunskap för att främja utbyggnad av markmonterade solcellsanläggningar även på nordliga breddgrader. Lönsamheten för ett högre montage undersöktes genom en jämförelse mellan ett prisexempel från en uppförd solpark och ett uppskattat produktionsbortfall från solparken i Östersund vid en teoretiskt lägre monteringshöjd. Det visade att en höjning av Östersundsparken från 50 till 90 centimeter skulle betala av sig enbart genom tillskottet i produktion under perioden februari till april de tre första vintrarna. / Ground-mounted PV installations in northern Sweden need to consider the presence of snow and the risk of ground interference, meaning that the buildup of snow in front of the panels prevents the snow accumulated on top from sliding off. The result is shading of the panels, which in turn reduces or eliminates the electricity production. The purpose of this work was to answer questions regarding the mounting height required to avoid this problem and whether the increased one-time cost for higher mounting is compensated for by the enhanced production during winter months. The method consisted mainly of comparing production data from a solar park in Östersund to solar radiation values and snow depth from SMHI to determine the effect of snow shading on production and the outcome at different installation heights of the plant. The results showed that there is great potential for valuable energy production during the late winter season, provided that ground interference is not present. This is probably due to high albedo from snow-covered ground and lower air temperatures resulting in a positive impact on the efficiency of the modules. A computational model was developed to estimate a suitable mounting height for a solar park based on the intended design and expected snow depth at the site. The intention is that the model can contribute to increased knowledge to promote the deployment of ground-mounted PV systems in northern latitudes. The profitability of higher mounting was investigated by comparing a price example from an existing solar facility and an estimated production loss from the solar park in Östersund at a theoretical lower mounting height. It showed that  increasing the height of the Östersund site from 50 to 90 centimeters in front would pay off solely on the enhanced production during the period February to April of the first three winters.

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