Theoretical Evaluation of Anisotropic Reflectance Correction Approaches for Addressing Multi-Scale Topographic Effects on the Radiation-Transfer Cascade in Mountain Environments

Research involving anisotropic-reflectance correction (ARC) of multispectral imagery to account for topographic effects has been ongoing for approximately 40 years. A large body of research has focused on evaluating empirical ARC methods, resulting in inconsistent results. Consequently, our research objective was to evaluate commonly used ARC methods using first-order radiation-transfer modeling to simulate ASTER multispectral imagery over Nanga Parbat, Himalaya. Specifically, we accounted for orbital dynamics, atmospheric absorption and scattering, direct- and diffuse-skylight irradiance, land cover structure, and surface biophysical variations to evaluate their effectiveness in reducing multi-scale topographic effects. Our results clearly reveal that the empirical methods we evaluated could not reasonably account for multi-scale topographic effects at Nanga Parbat. The magnitude of reflectance and the correlation structure of biophysical properties were not preserved in the topographically-corrected multispectral imagery. The CCOR and SCS+C methods were able to remove topographic effects, given the Lambertian assumption, although atmospheric correction was required, and we did not account for other primary and secondary topographic effects that are thought to significantly influence spectral variation in imagery acquired over mountains. Evaluation of structural-similarity index images revealed spatially variable results that are wavelength dependent. Collectively, our simulation and evaluation procedures strongly suggest that empirical ARC methods have significant limitations for addressing anisotropic reflectance caused by multi-scale topographic effects. Results indicate that atmospheric correction is essential, and most methods failed to adequately produce the appropriate magnitude and spatial variation of surface reflectance in corrected imagery. Results were also wavelength dependent, as topographic effects influence radiation-transfer components differently in different regions of the electromagnetic spectrum. Our results explain inconsistencies described in the literature, and indicate that numerical modeling efforts are required to better account for multi-scale topographic effects in various radiation-transfer components.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Étude des mouvements de fumée induits par les incendies de toits solaires

Abstract: Nowadays, there is a consensus, specifically among the Intergovernmental Panel on Climate Change (IPCC), that human activities have a huge impact on the ecosystem. Among all human activities, the release of greenhouse gases (GHG) plays an extremely important role in the impact on the environment, e.g., heat waves, global warming, sea level elevation, etc. Meanwhile, it is a frequently stated issue that GHG emissions from the building sector account for 40% of overall growth. To avoid further environmental deterioration, the concept of carbon neutrality was proposed, in other words, to limit the world average temperature rise to 1.5 ºC by 2050. To achieve this goal, the share of total energy from non-fossil sources (new energy technology) must increase from 27% (2019) to 60% (2050). Solar power, as one of the best choices of new energy technology, reaches a total installed capacity of 942 GW in 2021, furthermore, the total installed capacity is forecast to exceed 1 terawatt (TW) cumulatively in 2022. On the other hand, the increasing installed capacity of photovoltaic (PV) panels poses a new challenge; PV-related fire. According to statistical analysis, each megawatt of installed capacity of PV panels causes 0.0289 fires per year. That is, in 2022, there will be nearly 30,000 PV-related fires worldwide. These are not just predictions. PV-related fires are actually occurring. From 2005 to 2012, annual PV-panel-related fires increased from 1 to 53 in Germany; there were more than 600 PV-panel-related fires in Italy in 2016, and from 2018 to 2020, 66 PV-panel-related fires were reported in the Netherlands. Despite the public's concern about the increasing number of PV-related fires, there is still very little research on the subject. This not only threatens the safety of public life but also hinders the promotion of new energy technologies (solar energy). Previous studies have shown that solar panels emit large amounts of toxic gases containing heavy metals when burned. Meanwhile, most solar panels are installed on the roof of a house. Therefore, to bridge these research gaps, it is necessary and urgent to investigate the mechanism of smoke spread from solar roof fires with wind effect. To achieve the objective, a non-fireproof wind tunnel experiment is designed based on the helium-smoke similarity and Froude modeling. First, a new theory of helium similarity is proposed, which uses helium release as the surrogate of real fire smoke. Fluid velocities remain consistent between the helium test and fire smoke test, simultaneously, the dimensionless concentration will be equal to the dimensionless temperature. Second, a new scale method is also built to achieve compatibility among the sub-scale helium model, sub-scale smoke model, and full-scale smoke model. Third, the wind tunnel test is conducted based on vent size, various roof angles, wind speed, and heat release rate (HRR). Fourth, the Computational Fluid Dynamics (CFD) simulations are run and validated by the Fire Dynamics Simulator (FDS) based on the wind tunnel test in the sub-scale model and full-scale model, as well as fire smoke scenarios and helium scenarios. Then, the theory of helium similarity and the proposed scale method are verified by comparing the simulation results. Finally, the parametric study is performed to obtain the critical values of vent size, roof angle, wind speed, and HRR. By comparing the results between the simulation and experiment, the FDS model is validated with good agreement: average differences of 11.95% for velocity and 19.04% for helium concentration. The similarity between the helium test and the fire smoke test is also justified by the difference in simulation results (0.39% of velocity and 1.95% of dimensionless temperature and concentration). Then compatibility can be achieved between the sub-scale model and full-scale model results (the average difference of 7.02% for dimensionless velocity and 7.87% for temperature). Once the compatibility between the fire smoke test in the full-scale model and the helium test in the sub-scale model is verified, the parametric study is conducted. The results show that the occupants only have four minutes of evacuation time during a solar roof fire with a skylight. The 15° roof is the most dangerous scenario; conversely, 45° and 60° roof angles are the safest solar roof design. The critical wind speed is 10 m/s at full scale and has the most negative impact on the occupant’s safety. The higher the HRR, the more the smoke infiltrates. The smaller roof vent can effectively avoid smoke infiltration. The results of the vector field illustrate that smoke infiltration is caused by the reverse flow at the region of separation.De nos jours, il existe un consensus sur le fait que les activités humaines ont un impact énorme sur l'écosystème, plus précisément le Groupe d'experts intergouvernemental sur l'évolution du climat (GIEC). Parmi toutes les activités humaines, l'émission de gaz à effet de serre (GES) joue un rôle extrêmement important dans l'impact sur l'environnement, par exemple, les vagues de chaleur, le réchauffement de la planète, l'élévation du niveau de la mer, etc. Parallèlement, il est fréquent de constater que les émissions de GES du secteur du bâtiment représentent 40 % de la croissance globale. Pour éviter toute détérioration supplémentaire de l'environnement, le concept de neutralité carbone a été proposé, en d'autres termes, limiter l'augmentation de la température moyenne mondiale à 1,5 ºC d'ici 2050. Pour atteindre cet objectif, la part de l'énergie totale provenant de sources non fossiles (nouvelles technologies énergétiques) doit passer de 27 % (2019) à 60 % (2050). L'énergie solaire, qui constitue l'un des meilleurs choix en matière de nouvelles technologies énergétiques, atteint une capacité totale installée de 942 GW en 2021. En outre, la capacité totale installée devrait dépasser 1 TW cumulé en 2022. D'autre part, l'augmentation de la capacité installée des panneaux photo-voltaïques (PV) pose un nouveau défi : les incendies liés en PV. Selon une analyse statistique, chaque mégawatt de capacité installée de panneaux PV provoque 0,0289 incendie par an. Autrement dit, en 2022, il y aura près de 30 000 incendies liés au PV dans le monde. Il ne s'agit pas de simples prédictions. Les incendies liés au PV se produisent réellement. De 2005 à 2012, les incendies annuels liés aux panneaux photo-voltaïques sont passés de un à 53 en Allemagne ; plus de 600 incendies liés aux panneaux photo-voltaïques ont été recensés en Italie en 2016 et, de 2018 à 2020, 66 incendies liés aux panneaux photo-voltaïques ont été signalés aux Pays-Bas. Malgré l'inquiétude du public face à l'augmentation du nombre d'incendies liés aux panneaux photovoltaïques, il existe encore très peu de recherches sur le sujet. Cela menace non seulement la sécurité de la vie publique, mais entrave également la promotion des nouvelles technologies énergétiques (énergie solaire). Des études antérieures ont montré que les panneaux solaires émettent de grandes quantités de gaz toxiques contenant des métaux lourds lorsqu'ils brûlent. Par ailleurs, la plupart des panneaux solaires sont installés sur le toit de la maison. Par conséquent, pour combler ces lacunes dans la recherche, il est nécessaire et urgent d'étudier le mécanisme de propagation de la fumée d'un feu de toit solaire avec effet du vent. Pour atteindre cet objectif, une expérience de soufflerie non résistante au feu est conçue sur la base de la similitude hélium-fumée et de la modélisation de Froude. Tout d'abord, une nouvelle théorie de la similitude de l'hélium est proposée, qui utilise le dégagement d'hélium comme substitut de la véritable fumée d'incendie. Les vitesses des fluides restent cohérentes entre l'essai à l'hélium et l'essai à la fumée d'incendie, simultanément, la concentration sans dimension sera égale à la température sans dimension. Deuxièmement, une nouvelle méthode d'échelle est également mise au point pour assurer la compatibilité entre le modèle à l'hélium à échelle réduite, le modèle de fumée à échelle réduite et le modèle de fumée à échelle réelle. Troisièmement, le test en soufflerie est réalisé en fonction de la taille de l'évent, des différents angles du toit, de la vitesse du vent et du taux de dégagement de chaleur (HRR). Quatrièmement, les simulations de dynamique des fluides numériques (CFD) sont exécutées et validées par le Fire Dynamics Simulator (FDS) sur la base des essais en soufflerie dans le modèle à échelle réduite et le modèle à échelle réelle, ainsi que dans les cas de fumée de feu et d'hélium. Ensuite, la théorie de la similitude de l'hélium et la méthode d'échelle proposée sont vérifiées en comparant les résultats de la simulation. Enfin, l'étude paramétrique est réalisée pour obtenir les valeurs critiques de la taille de l'évent, de l'angle du toit, de la vitesse du vent et du HRR. En comparant les résultats entre la simulation et l'expérience, le modèle FDS est validé avec un bon accord: différences moyennes de 11,95 % pour la vitesse et de 19,04 % pour la concentration d'hélium. La similitude entre l'essai à l'hélium et l'essai aux fumées d'incendie est également justifiée par la différence entre les résultats de la simulation (0,39 % pour la vitesse et 1,95 % pour la température et la concentration sans dimension). Ensuite, la compatibilité peut être obtenue entre les résultats du modèle à échelle réduite et ceux du modèle à échelle réelle (la différence moyenne est de 7,02 % pour la vitesse sans dimension et de 7,87 % pour la température). Une fois que la compatibilité entre l'essai de fumée d'incendie dans le modèle à l'échelle réelle et l'essai à l'hélium dans le modèle à l'échelle secondaire est vérifiée, l'étude paramétrique est menée. Les résultats montrent que les occupants ne disposent que de quatre minutes d'évacuation lors d'un incendie de toiture solaire avec lanterneau. Le toit de 15° est le scénario le plus dangereux, à l'inverse, les angles de toit de 45° et 60° sont les conceptions les plus sûres pour le toit solaire. La vitesse critique du vent est de 10 m/s à l'échelle réelle et a l'impact le plus négatif sur la sécurité des occupants. Plus le HRR est élevé, plus la fumée s'infiltre. L'évent de toit plus petit peut éviter efficacement l'infiltration de fumée. Les résultats du champ vectoriel montrent que l'infiltration de fumée est causée par l'écoulement inverse dans la région de séparation

The Photosynthetic Action Spectra of the Phytoplankton and Their Role in Governing Spatial and Temporal Distribution: A Numerical Modeling Approach

In the present study a numerical modeling approach is employed to examine the role of division spedific differences in photosynthetic action spectra in governing the relative size of diatom and dinoflagellate carbon synthesis along various marine light regime gradients. A radiative transfer model taking into account both Rayleigh and Mie atmospheric optical properties is employed to define the light regime incident on the sea surface. The hydrospheric light regime is defined by an exponential decay model with a correction for diffuse back scatter. Taken together, the atmospheric and hydrospheric models define the spectral composition and intensity of light in the sea as a function of solar altitude and depth. This permits the simulation of realistic spectral gradients along various temporal and spatial dimensions of the marine environment: diurnal, seasonal, vertical, and latitudinal. A spectrally sensitive model of photosynthesis is employed to determine the rates at which carbon compounds are synthesized a t various points along these gradients. The ratio (between dinoflagellate and diatom carbon synthesis is determined by taking into account differences in division specific photosynthetic action spectra

Greening Greenpoint: Investigating Technology and Environment-based Design

This thesis investigates architectural design with a focus on technology and parametric, or computational, design strategies in relation to environmental simulation and sustainability. While numerous studies of new digital and parametric design technologies have been undertaken, few discuss their potential application or synergy with sustainable or environmentally focused design. However, there is increasing interest in bridging the perceived gap between these areas of focus in architectural design, as will be discussed in a section on recent symposia related to performance and design technologies. The research project seeks to apply insight gained from these studies to a design project to be located in the Greenpoint neighborhood of Brooklyn, New York. The project type is a library and research center which would serve as a knowledge base and community hub for the study and discussion of environmental protection, sustainability, and conservation. As a hybrid archive, learning center, forum, and repository of information, it would aim to serve as a catalyst for the ongoing attempts to remediate the environmental conditions of nearby Newtown Creek and adjacent land, which has been subjected to severe environmental degradation as a result of a century and half of industrial activities related to oil refining and storage. The eastern portion of Greenpoint along Newtown Creek has been designated a superfund site as a result of millions of gallons of oil spillage occurring over an uncertain length of time, much of which remains below ground today. Additionally, the surrounding water bodies have been polluted from the discharge of excess wastewater due to overflow of the city’s combined sewer system during large storms. Thus the community and city face numerous environmental challenges and would be well served by a facility which would provide a research base and meeting place. The project also engages with an additional set of conditions related to the site. Recent zoning changes have been approved which will convert the formerly industrial East River waterfront to a dense residential zone. While the zoning aims to establish a public space along the waterfront, it will also likely result in residential towers vastly out of scale and context with adjacent neighborhood, which includes an important historic district, and a diverse population. The project seeks to place instead, at the tip of the peninsula which was once named for its greenness, a public space dedicated to its restoration

Energy performance of water strip modules for industrial heating in real operation conditions: Steady-state and CFD analyses

The objective of this study is the theoretical evaluation of the energy performance of a radiant strips heating system fed with hot water by varying the operating conditions. First, the convective coefficients and the heating power (both convective and radiant parts) of the heating system are evaluated in steady-state conditions by simulating heat exchange similar to real operating conditions (such as the presence of a ventilation system, the opening of doors, windows, or skylights, etc.), in comparison with the nominal data. To carry out this preliminary assessment, different references in the scientific literature are considered with respect to experimental measurements and numerical simulations for similar applications. The steady-state analysis revealed that the increase in the overall yield of the heating strips, compared to the data measured according to the EN 14,037 standard, is in the order of 30%. Afterward, a CFD analysis is reported to dynamically study the effect of the above-mentioned typical situations of real operation of the system in industrial sheds. The CFD analysis confirms that the presence of constant air exchange leads to an improvement of more than 30% in the performance of the water strip system. The main conclusion is that designing the water strip system following the EN 14,037 standard probably will oversize the industrial heating plant

PS Poster Session - All

This document includes all poster sessions at the IBPC 2018

Efficient global illumination calculation for inverse lighting problems

La luz es un elemento clave en la manera en que percibimos y experimentamos nuestro entorno. Como tal, es un objeto mas a modelar en el proceso de diseño, de forma similar a como ocurre con las formas y los materiales. Las intenciones de iluminacion (LI) son los objetivos y restricciones que el diseñador pretende alcanzar en el proceso del diseño de iluminaci´on: ¿qué superficies se deben iluminar con luz natural y cuales con luz artificial?, ¿qué zonas deben estar en sombra?, ¿cuales son las intensidades maximas y mínimas permitidas? Satisfacer las LI consiste en encontrar la ubicacion, forma e intensidad adecuada de las fuentes luminosas. Este tipo de problemas se define como un problema inverso de iluminacion (ILP) que se resuelve con tecnicas de optimizacion. En el contexto anterior, el objetivo de esta tesis consiste en proponer metodos eficientes para resolver ILP. Este objetivo es motivado por la brecha percibida entre los problemas habituales de diseño de iluminacion y las herramientas computacionales existentes para su resolucion. Las herramientas desarrolladas por la industria se especializan en evaluar configuraciones de iluminacion previamente diseñadas, y las desarrolladas por la academia resuelven problemas relativamente sencillos a costos elevados. Las propuestas cubren distintos aspectos del proceso de optimizacion, que van desde la formulacion del problema a su resolucion. Estan desarrolladas para el caso en que las superficies poseen reflexion e iluminacion difusas y se basan en el calculo de una aproximacion de rango bajo de la matriz de radiosidad. Algunos resultados obtenidos son: el calculo acelerado de la radiosidad de la escena en una unidad de procesamiento gr´afico (GPU); el uso de la heuristica \201Cvariable neighborhood search\201D (VNS) para la resolucion de ILP; el planteo de una estructura multinivel para tratar ILP de forma escalonada; y el uso de tecnicas para optimizar la configuracion de filtros de luz. Otros resultados obtenidos se basan en la formulacion de las LI en funcion de la media y desviacion estandar de las radiosidades halladas. Se propone un metodo para generar LI que contengan esos parametros estadisticos, y otro metodo para acelerar su evaluacion. Con estos resultados se logran tiempos de respuesta interactivos. Por último, las tecnicas anteriores adolecen de una etapa de pre-cómputo relativamente costosa, por tanto se propone acelerar el calculo de la inversa de la matriz de radiosidad a partir de una muestra de factores de forma. Los métodos aquí presentados fueron publicados en seis articulos, tres de ellos en congresos internacionales y tres en revistas arbitradas.Light is a key element that influences the way we perceive and experience our environment. As such, light is an object to be modeled in the design process, as happens with the forms and materials. The lighting intentions (LI) are the objectives and constraints that designers want to achieve in the process of lighting design: which surfaces should be illuminated with natural and which with artificial light?, which surfaces should be in shadow?, which are the maximum and minimum intensities allowed? The fulfillment of the LI consists in finding the location, shape and intensity appropriate for the light sources. This problem is defined as an inverse lighting problem (ILP), solved by optimization techniques. In the above context, the aim of this thesis is the proposal of efficient methods to solve ILP. This objective is motivated by the perceived gap between the usual problems of lighting design, and the computational tools developed for its resolution. The tools developed by the industry specialize in evaluating previously designed lighting configurations, and those developed by the academia solve relatively simple problems at a high computational cost. The proposals cover several aspects of the optimization process, ranging from the formulation of the problem to its resolution. They are developed for the case in which the surfaces have Lambertian reflection and illumination, and are based on the calculation of a low rank approximation to the radiosity matrix. Some results are: rapid calculation of radiosity of the scene in a graphics processing unit (GPU), the use of heuristics “variable neighborhood search” (VNS) for solving ILP, the proposition of a multilevel structure to solve ILP in a stepwise approach, and the use of these techniques to optimize the configuration of light filters. Other results are based on the formulation of LI that use the mean and standard deviation of the radiosity values found. A method is proposed for generating LI containing these parameters, and another method is developed to speed up their evaluations. With these results we achieve interactive response times. Finally, the above techniques suffer from a costly pre-computing stage and therefore, a method is proposed to accelerate the calculation of the radiosity inverse matrix based on a sample of the form factors. The methods presented here were published in six articles, three of them at international conferences and three in peer reviewed journals

Synthetic image generation of factory stack and water cooling tower plumes

Remote sensing of cooling tower and factory stack plumes may provide unique information on the constituents of the plume. Potential information of the power generated by the plant or the chemical composition of the factory products may be gathered from thermal emission and absorption in the infrared band, or from scattering of light in the visible band. A new model for generating synthetic images of plumes has been developed using DIRSIG, a radiometrically based ray-tracing code. Existing models that determine the characteristics of the plume (constituents, concentration, particulate sizing, and temperature) are used to construct the plume in DIRSIG. The effects of scattered light using Mie theory and radiative transfer, as well as thermal self-emission and absorption from within the plume, are modeled for different regions of the plume. Both single and multiple scattering methods are available. The ray-tracing accounts for radiance from the plume, atmosphere, and background. \u27 Synthetic generated images of a cooling tower plume, composed of water droplets, and a factory stack plume, composed of methyl chloride, are produced for visible, MWIR, and LWIR bands. Images of the plume from different sensor platforms are also produced. Observations are made on the interaction between the plume and its background and possible effects for remote sensing. Images of gas plumes using a hyperspectral sensor are illustrated. Several sensitivity studies are done to demonstrate the effects of changes in plume characteristics on the resulting image. Inverse algorithms that determine the plume effluent concentration are tested on the plume images. A validation is done on the gas plume model using experimental data collected on a SF6 plume. Results show the integrated plume model to be in good agreement with the actual data from five to one hundred meters from the stack exit. The scattering models are tested against MODTRAN. The validity and limitations of these models are discussed as a result of these tests. Finally two atmospheric scattering phenomena are illustrated to demonstrate qualitatively the scattering models