Orientador: Jairo Osvaldo Cazetta / Banca: Marcelo Murad Magalhães / Banca: Paulo Cesar Magalhães / Banca: Domingos Fornasieri Filho / Banca: Durvalina Maria Mathias dos Santos / Resumo: Com o objetivo de avaliar diferentes estresses sobre o acúmulo e partição de massa seca, abortamento, desenvolvimento, produção de grãos e concentração de metabólitos glicídicos e nitrogenados em plantas de milho, conduziuse um experimento em casa de vegetação. Os tratamentos foram: testemunha; plantas com desfolhamento de 66%; omissão do nitrogênio; déficit hídrico (20 - 30% da capacidade de retenção); sombreamento de 70%. Os estresses foram impostos dos dois aos quarenta dias após a polinização (DAP) e as avaliações realizadas em cinco coletas aos 0, 10, 20, 30 e 40 DAP. A omissão de N na fase reprodutiva não afetou a massa seca das plantas e não promoveu alterações nos grãos das plantas de milho, em função da grande remobilização deste elemento acumulado nas folhas e colmos durante o período vegetativo. O desfolhamento reduziu o acúmulo de massa seca no colmo e na espiga, causou abortamento de grãos, não afetou a massa dos grãos remanescentes, resultando em menor número e produção de grãos por planta. O sombreamento intensificou a translocação de fotossintatos do colmo e folhas para os grãos, causou redução no acúmulo de massa seca na planta, abortamento de grãos, menor peso dos grãos remanescentes, menor acúmulo de amido e menor produção de grãos por planta. O déficit hídrico reduziu a área foliar, a fotossíntese, o período de enchimento dos grãos, o acúmulo de MS na planta e a translocação de fotoassimilados para os grãos, resultando em abortamento de grãos do ápice da espiga, acúmulo de açúcares redutores e aminoácidos livres nas folhas e colmos e menor massa de grãos e produção por planta. A redução na produção foi maior no estresse por déficit hídrico, sombreamento de 70%, desfolhamento de 66% e deficiência de N, sendo o número de grãos por espiga e peso médio dos grãos os componentes da produção mais afetados. / Abstract: To evaluate the effect of different stress on the accumulation and distribution of dry matter, abortion, development and production of grains and concentration of glycidic and nitrogen metabolites in maize plant, it was conducted an experiment on greenhouse conditions. The following treatments were used: control; defoliation (plants 66% defoliated); nitrogen omission; water deficit (20 - 30% of the retention capacity); shading (70%). The stress factors were imposed from two to forty days after pollination (DAP) and the analyses at 0, 10, 20, 30 and 40 DAP. The nitrogen omission at the reproductive stage did not affect plant dry mass or grains because of the high rate of remobilization of the N accumulated in leaves and stems during the vegetative stage. Defoliation reduced the dry matter accumulation in the stem and ears, increased kernel abortion, no caused any effect on photoassimilate translocation or weight from remaining grains. Also, resulted in a decrease on the total-N level, amino acids, grain reducing sugars and starch, fewer grains and lower production per plant. Shading intensified photoassimilate translocation indicating that in shaded plants the photosynthesis limitation is supplied by the high remobilization rate of reducing sugars, sucrose and starch from the stem and leaves to the grain. However, this stress causes reduction of dry matter accumulation, kernel abortion, and lower weight of remaining grains, starch accumulation and production of grains per plant. The water deficit reduced leaf area, photosynthesis, grain filling period, dry matter accumulation and photoassimilate translocation from vegetative organs to kernels, resulting in kernel abortion at the ear top, accumulation of reducing sugars and free amino acids in leaves and stems and lower weight of 1,000 grains and production per plant... (Complete abstract, click electronic address below) / Doutor

Context. In this thesis, a GPU-based light culling technique performed with conservative rasterization is presented. Accurate lighting calculations are expensive in real-time applications and the number of lights used in a typical virtual scene increases as real-time applications become more advanced. Performing light culling prior to shading a scene has in recent years become a vital part of any high-end rendering pipeline. Existing light culling techniques suffer from a variety of problems which clustered shading tries to address. Objectives. The main goal of this thesis is to explore the use of the rasterizer to efficiently assign convex light shapes to clusters. Being able to accurately represent and assign light volumes to clusters is a key objective in this thesis. Methods. This method is designed for real-time applications that use large amounts of dynamic and arbitrarily shaped convex lights. By using using conservative rasterization to assign convex light volumes to a 3D cluster structure, a more suitable light volume approximation can be used. This thesis implements a novel light culling technique in DirectX 12 by taking advantage of the hardware conservative rasterization provided by the latest consumer grade Nvidia GPUs. Experiments are conducted to prove the efficiency of the implementation and comparisons with AMD´s Forward+ tiled light culling are provided to relate the implementation to existing techniques. Results. The results from analyzing the algorithm shows that most problems with existing light culling techniques are addressed and the light assignment is of high quality and allows for easy integration of new convex light types. Assigning the lights and shading the CryTek Sponza scene with 2000 point lights and 2000 spot lights takes 2.92ms on a GTX970. Conclusions. The conclusion shows that the main goal of the thesis has been reached to the extent that all existing problems with current light culling techniques have been solved, at the cost of using more memory. The technique is novel and a lot of future work is outlined and would benefit the validity of the implementation if further researched.

The University of Arizona Main Campus is located in the city of Tucson, Arizona. A place that confronts high air temperatures and extreme solar radiation almost all year around. Currently, more than 38,000 students are enrolled as full-time facing the extreme climate conditions of heat. Thousands of students walk from one place to another experiencing uncomfortable walks causing them heat stress. Campus infrastructure is not capable to interact with the weather conditions of Tucson. The lack of shaded paths, materials with high emissivity of heat, nonnative vegetation, among other factors, make the walks unpleasant. This challenge affects people's health and consecutively the performance of cooling systems once the people enter to buildings overheated. Outdoor human thermal comfort in arid and desert areas is a relevant topic that carries implications and benefits on people and buildings performance. The amount and intensity of activities within individuals affects the level of comfort.

The Photovoltaic (PV) systems and the semiconductor PV technologies are heavily impacted by shading conditions; total or partial. Nearby residential buildings, commercial buildings, objects, etc. are likely to cause shade on the PV installations.  This study focuses on the evaluation of the effect of shading on thin-film PV modules, which were analyzed under two categories: single thin-film module and a string of modules installed at the University of Gävle, Sweden. The measurement was made by using METREL MI 3109 Euro test instrument. The study intends to help researchers to analyze the variation in the output performance parameters and behavior considering different types of shading on the thin-film modules. Experiments have been performed by creating full and partial shading (uniform and nonuniform) by using plastic foil, opaque board, wooden pole, and tape to emulate different types of natural shading conditions.  The findings show a loss in power due to shading. In the single thin-film modules, which do not have any diode between the cells; reverse breakdown, power dissipation and generation of hot spots are caused by the cells which are partially shaded.  In the string of modules installed at the University of Gävle, Sweden; under partial shading conditions the diodes are activated below certain voltage when current is high, leading to current bypass and therefore prevents the module from the damage caused by high heat generation. Under the condition of extremely low shading by a wooden pole, the diodes were not activated; however reverse breakdown was observed similar to the case of partial shading in single thin-film modules.

Many utility-scale solar farms use horizontal single axis tracking to follow the sun throughout the day and produce more energy. Solar farms on skewed topography produce complex shading patterns that require precise modeling techniques to determine the energy output. To accomplish this, MATLAB was used in conjunction with NREL weather predictions to predict shading shapes and energy outputs. The MATLAB models effectively predicted the sun’s position in the sky, panel tilt angle throughout the day, irradiance, cell temperature, and shading size. The Cal Poly Gold Tree Solar Farm was used to validate these models for various lengths of time. First, the models predicted the shading and power output for a single point in time. Four points of time measurements were taken; resulting in 6 to 32 percent difference in shade height, 5 to 60 percent difference for shade length, and 29 to 59 percent difference for power output. This shows the difficulty of predicting a point in time and suggests the sensitivity of numerous variables like solar position, torque tube position, panel tilt, and time itself. When predicting the power over an entire day, the power output curves for a single inverter matched almost exactly except for in the middle of the day due to possible inaccurate cell temperature modeling or the lack of considering degradation and soiling. Since the backtracking region of the power curve is modeled accurately, the optimization routine could be used to reduce interrow shading and maximize the energy output for a single zone of the solar field. By assuming every day is sunny, the optimization routine adjusted the onset of backtracking to improve the energy output by 117,695 kilowatt hours for the year or 8.14 percent compared to the nominal settings. The actual solar farm will likely never see this increase in energy due to cloudy days but should improve by a similar percentage. Further optimization of other zones can be analyzed to optimize the entire solar field.

no / Image gradients - smooth changes in color and luminance - may be caused by intrinsic surface reflectance properties or extrinsic illumination phenomena, including shading, shadowing, and inter-reflections. In turn, image gradients may provide the visual system with information concerning the origin of these factors, such as the orientation of surfaces with respect to the light source. Color gradients induced by mutual illumination (MI) may play a similar role to that of luminance gradients in shape-from-shading algorithms; it has been shown that 3D shape perception modulates the influence of MI on surface color perception (M. G. Bloj, D. Kersten, & A. C. Hurlbert, 1999). In this study, we assess human sensitivity to changes in color and luminance gradients that arise from changes in the light source position, within a complex scene. In Experiment 1, we tested whether observers were able to discriminate between gradients due to different light source positions. We found that observers reliably detected a change in the gradient information when the light source position differed by only 4 deg from the reference scene. This sensitivity was mainly based on the luminance information in the gradient (Experiments 2 and 3). Some observers make use of the spatial distribution of chromaticity and luminance values within gradients when discriminating between them (Experiment 4). The high sensitivity to gradient differences supports the notion that gradients contain information that may assist in the recovery of 3D shape and scene configuration properties.

The human visual system gathers information about three-dimensional object shape from a wide range of sources. How effectively we can use these sources, and how they are combined to form a consistent and accurate percept of the 3D world is the focus of much research. In complex scenes inter-reflections of light between surfaces (mutual illumination) can occur, creating chromatic illumination gradients. These gradients provide a source of information about 3D object shape, but little research has been conducted into the capabilities of the visual system to use such information. The experiments described here were conducted with the aim of understanding the influence of chromatic gradients from mutual illumination on 3D shape perception. Psychophysical experiments are described that were designed to investigate: If the human visual system takes account of mutual illumination when estimating 3D object shape, and how this might occur; How colour shading cues are integrated with other shape cues; The relative influence on 3D shape perception of achromatic (luminance) shading and chromatic shading from mutual illumination. In addition, one chapter explores a selection of mathematical models of cue integration and their applicability in this case. The results of the experiments suggest that the human visual system is able to quickly assess and take account of colour mutual illuminations when estimating 3D object shape, and use chromatic gradients as an independent and effective cue. Finally, mathematical modelling reveals that the chromatic gradient cue is likely integrated with other shape cues in a way that is close to statistically optimal.

No description available.

Made available in DSpace on 2015-05-14T12:09:17Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 11721835 bytes, checksum: d91df33daa9451f253a6f22c8d5b1f6b (MD5) Previous issue date: 2012-03-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This work addresses topics such as shading devices, shading and daylighting. It aims at verifying the efficiency of shading devices found classroom buildings at UFPB's campus I, with respect to shading and daylighting. The results of the research focus in the diagnosis of the solutions in the case study, by using three dimensional models (3D) and computer simulation. The digital models were constructed from data collected in field surveys. The computer programs used were the Solar Tool, Ecotect and Daysim. In parallel, we investigated a set of hypothetical situations, considering all the solutions found in the survey, in order to identify the performance of the solutions in other orientation facade. The evaluation of the models was made from performance measures such as the percentage of shading, percentage of sky visibility and useful daylight illuminances (UDI). From the results, we observed that: a) south-oriented façades with unprotected openings allow for environments with higher levels and better distribution of natural lighting; b) a large part of the orientation facade analyzed, except in the northwest and east, more than 50% of the samples obtained a good performance of daylighting; c) the percentage of shading is not enough to say whether an element of sunscreen is effective or not, which can generate misleading conclusions when used alone; d) the correlation of the performance of daylighting and performance of shading with the percentage of sky visibility, showed that for every orientation facade there is an optimal ratio between the percentage of shading and the percentage of sky visibility, and for the facade analyzed, the values of these measures are generally around 88.7% of shading of the opening and 8.1% of sky visibility. / Este trabalho aborda temas como elementos de proteção solar, sombreamento e iluminação natural. Tem como objetivo a verificação da eficiência de proteções solares encontradas em edificações de salas de aula no campus I da UFPB, no que diz respeito ao sombreamento e à iluminação natural. Os resultados da investigação centram-se no diagnóstico das soluções encontradas no estudo de caso, através da utilização de modelos tridimensionais (3D) e simulação computacional. Os modelos digitais foram construídos a partir de dados coletados em levantamento de campo. Os programas computacionais utilizados foram o Solar Tool, Daysim e o Ecotect. Em paralelo, foi investigado um conjunto de situações hipotéticas, considerando todas as soluções encontradas no levantamento, com objetivo de identificar o desempenho das soluções em outras orientações. A avaliação dos modelos foi feita a partir de medidas de desempenho como o percentual de sombreamento, percentual de visibilidade do céu e do useful daylight illuminances (UDI). Com os resultados obtidos foi possível observar que: a) fachadas com aberturas sem proteção orientadas para o Sul geram ambientes com melhores níveis e distribuição da iluminação natural; b) em grande parte das orientações analisadas, exceto na Noroeste e Leste, mais de 50% da amostra obteve um bom desempenho da iluminação natural; c) o percentual de sombreamento não é suficiente para afirmar se um sombreamento é eficaz ou não, podendo gerar conclusões equivocadas quando utilizado isoladamente; d) a correlação da performance da iluminação natural e do desempenho do sombreamento com o percentual de visibilidade do céu, mostrou que para cada orientação existe uma relação ideal do percentual de sombreamento com o percentual de visibilidade do céu, sendo que para as orientações analisadas os valores destas medidas se encontraram, em geral, próximo de 88,7% de sombreamento da abertura e 8,1% de visibilidade do céu.

Background. Hardware-accelerated ray tracing has enabled ray traced reflections for real-time applications such as games. However, the number of rays traced each frame must be kept low to achieve expected frame rates. Therefore, techniques such as rendering the reflections at quarter resolution are used to limit the number of rays traced each frame. The new hardware features inline ray tracing, and hardware variable rate shading (VRS) could be combined to limit the rays even further. Objectives. The first goal is to use hardware VRS to limit the number of rays even further than rendering the reflections at quarter resolution, while maintaining the visual quality in the final rendered image. The second goal is to determine if inline ray tracing provides better performance than using ray generation shaders. Methods. Experiments are performed on a ray traced reflections pipeline using different techniques to generate rays. The techniques use inline ray tracing, inline ray tracing combined with VRS, and ray generation shaders. These are compared and evaluated using performance tests and the image evaluator \FLIP. Results. The results show that limiting the number of rays with hardware VRS result in a performance increase. The difference in visual quality between using inline ray tracing with VRS and previous techniques remain comparable. The performance tests show that inline ray tracing performs worse than ray generation shaders with increased scene complexity. Conclusions. The conclusion is that hardware VRS can be used to limit the number of rays and achieve better performance while visual quality remain comparable to previous techniques. Inline ray tracing does not perform better than ray generation shaders for workloads similar to ray traced reflections. / Bakgrund. Hårdvaruaccelererad strålspårning har möjliggjort strålspårade reflektioner för realtidsapplikationer såsom spel. Däremot måste antalet strålar som spåras hållas lågt för att förväntade bildfrekvenser ska uppnås. Därför används renderings-tekniker som att rendera reflektioner i en fjärdedels upplösning för att begränsa mängden strålar. De nya teknikerna inline strålspårning och hårdvarubaserad variable rate shading (VRS) kan användas för att minska antalet strålar ytterliggare. Syfte. Det första målet är att använda hårdvarubaserad VRS för att minska antalet strålar ytterligare jämfört med att rendera reflektioner i en fjärdedels upplösning, men samtidigt upprätthålla den visuella kvalitén. Det andra målet är att avgöra om inline strålspårning ger bättre prestanda än att använda strålgenererings shaders för reflektioner. Metod. För att svara på forskningsfrågorna ufördes experiment på en strålspårad reflektionspipeline med olika tekniker för att generera strålar. Teknikerna som testas är inline strålspårning, inline strålspårning kombinerat med VRS, samt strålgenererings shaders. Dessa jämförs och evalueras med prestandatester och bild-evaulatorn \FLIP. Resultat. Resultaten visar att minska mängden strålar med hårdvarubaserad VRS resulterar i en prestandaökning. Skillnaden i visuell kvalité mellan inline strålspårning kombinerat med VRS och tidigare tekniker är jämförbara. Prestandatesterna visar att inline strålspårning presterar värre än strålgenererings shaders vid ökad scenkomplexitet. Slutsatser. Slutsatsen är att hårdvarubaserad VRS kan användas för att minska antalet strålar och resultera i bättre prestanda, medan den visuella kvalitén är jämförbar med tidigare tekniker. Inline strålspårning ger inte bättre prestanda än strålgenererings shaders vid strålspårade reflektioner och liknande arbetsbelastning.