Este trabalho apresenta alguns aspectos específicos sobre o tema “proteção de estruturas contra descargas atmosféricas", principalmente no que se refere ao uso de partes estruturais das edificações como integrantes do sistema de proteção. São discutidos neste trabalho diversos pontos polêmicos referentes ao tema, tais como: captores especiais, o sistema dissipativo e o uso das ferragens das colunas de concreto armado como parte dos subsistemas de descida e de aterramento. São abordados, também, os principais danos que podem ocorrer nas edificações devido às descargas atmosféricas, principalmente quando a proteção utilizar partes naturais da estrutura, tais como: os telhados metálicos e as emendas das ferragens das colunas de concreto armado. Após uma verificação do estado da arte no assunto, onde são estudados diversos trabalhos, normas e livros sobre as características das descargas, sobre os danos oriundos das descargas, blindagens, medições de campos eletromagnéticos, distribuição de correntes e sobre a normalização e ensaios referentes à proteção de estruturas contra descargas atmosféricas, o assunto foi estudado em três partes que compõem os subsistemas do SPDA. No subsistema de captação, os danos em telhas metálicas e de concreto protendido foram estudados através de ensaios e verificações teóricas e, principalmente, experimentais. No subsistema de descida, o estudo experimental deu enfoque às emendas das ferragens e ao uso destas como descidas naturais. Finalmente, no subsistema de aterramento, as fundações das edificações foram estudadas através de verificações experimentais como parte do aterramento. Este trabalho acrescenta ao conhecimento atual sobre o assunto, diversas particularidades não contempladas nas normas e nas publicações mais recentes no que tange à proteção de estruturas contra as descargas atmosféricas utilizando partes naturais das edificações. / This work presents some specific aspects on the subject “lightning protection of structures“, mainly when the use of structural parts of the buildings as part of the protection systems is concerned. Several polemical issues are discussed, such as: special air-termination, the dissipation array system and the use of steel-reinforcing rods of the reinforced concrete columns as part of the down-conductor system and of the earth-termination system. Also treated is the main damage that can occur to the buildings due to lightning, mainly when the protection system uses the natural components of the structures, such as: the metallic rooftops and the joints of the steel-reinforcing rods of the reinforced concrete columns. After examining the state-of-the-art in the subject, which analyses several papers, standards and books about lightning characteristics, damage resulting from lightning, shieldings, measurements of electromagnetic fields, distribution of currents and about standardisation and tests related to the protection of structures against lightning, the subject was studied in the three parts that compose the lightning protection systems. In the air-termination system, the damage to metallic rooftops and to pre-stressed concrete rooftop tiles was studied by means of tests and theoretical and mainly experimental analyses. In the down-conductor system, the experimental study focused on the joints of the steel-reinforcing rods and on the use of these as natural down-conductors. Finally, in the earth-termination system, the foundations of the buildings were studied (as part of the grounding) through experimental analyses. This work adds to the current knowledge about the subject several particularities which are not observed in the standards or in the most recent publications concerning the lightning protection systems in buildings that use their natural components for this purpose.

A beta-alumina de sódio é uma cerâmica condutora de íons Na+ utilizada como eletrólito sólido em baterias de sódio para armazenamento de energias intermitentes como energia solar e eólica. Devido ao alto teor de sódio, esse material é instável a altas temperaturas, podendo sofrer variações de composição durante a etapa de sinterização convencional que utiliza altas temperaturas por longos períodos de tempo. A sinterização flash é uma técnica de sinterização ativada por corrente elétrica que proporciona a densificação de compactos cerâmicos em poucos segundos, a temperaturas notavelmente mais baixas que as convencionais. Uma vez obrigatória a passagem de corrente elétrica através da amostra, a sinterização flash de qualquer material condutor parece bastante razoável. Não obstante, até o presente momento a maioria dos trabalhos publicados sobre o assunto aborda apenas condutores de vacância de oxigênio ou semicondutores, materiais compatíveis com eletrodos de platina (Pt). Nesse trabalho a sinterização flash de um condutor catiônico foi estudada utilizando-se a beta-alumina como material modelo. A beta-alumina foi sintetizada pelo método dos precursores poliméricos, caracterizada e então submetida à sinterização flash. O material de eletrodo padrão (platina) provou ser um eletrodo bloqueador em contato com a beta-alumina. O sucesso da sinterização flash foi determinado pela troca do material de eletrodo por prata (Ag), o que possibilitou uma reação eletroquímica reversível nas interfaces eletrodo-cerâmica e possibilitou a obtenção de um material densificado com morfologia e composição química homogêneas. Devido à metaestabilidade da beta-alumina, a atmosfera dos experimentos precisou ser alterada para manter a integridade desse material rico em um metal alcalino (Na+). A sinterização flash de um condutor catiônico é apresentada pela primeira vez na literatura e ressalta a importância da reação de eletrodo, que é um fator limitante para o sucesso da sinterização flash e precisa ser estudada e adaptada para cada tipo de material. / Sodium beta-alumina is a Na+ ions conductor ceramic used as solid electrolyte in sodium batteries for energy storage in solar and eolic plants. Due to its high content of sodium, this material is instable at high temperatures and can suffer decomposition during conventional sintering (high temperatures for long periods of time). Flash sintering is an electric current activated sintering technique which promotes the densification of ceramic powder compacts in a few seconds at significantly lower temperatures than conventional sintering. Since in flash sintering the electric current flows through the sample, the flash sintering of any conductor material seems to be reasonable. Nevertheless, up to this date all published papers concern flash sintering of oxygen vacancies conductors or semi-conductors, materials which are compatible with platinum (Pt) electrodes. In this work the flash sintering of the cationic conductor betaalumina was studied. Beta-alumina was synthetized by the polymeric precursors method, characterized and then it was submitted to flash sintering. Platinum electrode was shown to be a blocking electrode for beta-alumina. Flash sintering success was determined by the change in electrode\'s material to silver (Ag), which made possible the reversible electrochemical reaction at the electrode-electrolyte interfaces and preserved chemical composition and morphology after flash. Due to this electrolyte metastability, atmosphere had to be changed in order to preserve the chemical composition of an alkali-rich (Na+) material such as beta-alumina. The flash sintering of a cationic conductor is shown for the first time in the literature and highlights the relevance of electrode reaction, which is a limiting point to the success of a flash sintering and needs to be well studied and adapted to each type of material.

abstract: Severe weather affects many regions of the United States, and has potential to greatly impact many facets of society. This study provides a climatological spatial analysis by county of severe weather warnings issued by the National Weather Service (NWS) between January 1st, 1986 to December 31st, 2017 for the contiguous United States. The severe weather warnings were issued for county-based flash flood, severe thunderstorm, and tornado phenomena issued through the study period and region. Post 2002 severe weather warnings issued by storm warning area were included in this study in the form of county-based warnings simultaneously issued for each affected county. Past studies have researched severe weather warnings issued by the NWS, however these studies are limited in geographic representation, study period, and focused on population bias. A spatial analysis of severe weather warning occurrences by county identify that (a) highest occurrences of flash flood warnings are located in the desert Southwest and Texas, (b) severe thunderstorm warning occurrence is more frequent in Arizona, portions of the Midwest, the South, and the Mid and South Atlantic states, (c) the tornado activity regions of Tornado Alley and Dixie Alley (i.e. Colorado, Kansas, Oklahoma, Arkansas, Texas, Louisiana, Mississippi, Alabama, Tennessee, and Illinois) contained the highest occurrences of tornado warnings, and (d) the highest instances of aggregate warning occurrences are found in the desert Southwest, the Midwest, and the Southern regions of the United States. Generally, severe weather warning “hot spots” tend to be located in those same regions, with greater coverage. This study concludes with a comparison of local maxima and general hot spot regions to expected regions for each phenomenon. Implications of this study are far reaching, including emergency management, and has potential to reduce risk of life. / Dissertation/Thesis / Masters Thesis Geography 2019

Pipe and ring blanks can be produced in several different ways. Today's focus on environmental effects motivates companies to develop processes that are as efficient as possible in their production. Ringsvets AB is a company that produces pipe and ring blanks from a flat stock by rolling and welding the piece to make it stay in its desired form. The direct benefit of the method is the minimizing of material loss, and it has thereby both environmental and economical advantages. The downside of the method is that the processes involved changes the mechanical behavior of the ring, locally around the weld zone. The focus of this master thesis is the processes and how they affect the material, both microstructure and behavior. The processes involved are; rolling, welding, shaping, brushing, forging, heat treatment, and calibration. The purpose of this work was to elevate the knowledge and understanding of the processes at Ringsvets. The goals were to give a theoretical description of them along with practical test results and explanations of how and why they function in reality. A literature study has been conducted which provided a theoretical basis on how the material reacts on certain processes. Practical examination of samples from current production has been done to get evidence of how well the processes are used, and how well they function, in today's production. Lastly, the main focus of the thesis, an evaluation has been made; do theory and practice correlate, and should anything be changed to correlate better? The results showed that the first operations do not alter the material behavior to an unacceptable extent. Forging, on the other hand, gives the material a very high hardness in the weld zone, and that needs to be corrected. The following heat treatment should compensate for that in a perfect world, but does not in reality. The finished ring shows good properties in general but with places where the heat treatment has failed to correct the uneven behavior induced by earlier operations. The heat treatment requires some adjustments before it functions as intended. Some grainshas not been recrystallized which makes them very hard and non-ductile. Future tests using a higher temperature or a longer heat treatment time would reveal the best way to adjust the heat treatment to obtain the desired properties. Other changes in the processes could also be benecial. Interesting things to try and change would, for example, be the degree of deformation in the forging, which affects the recrystallization temperature. Notes should be taken that this examination is done on just one sample of just one size. Analyses of different samples of different sizes should be done to ensure of the accuracy of the examination.

Pioneering work performed by Rosalind Franklin over half a century ago provided the first structural models of two distinct carbon types: those that become graphitic during carbonization at high temperatures, and those that do not. Moreover it is known that certain properties of carbonaceous materials including combustion, surface area, electrical resistivity, and catalytic properties are influenced by mineral impurities. The nature of this division in biocarbon structure and the known effects of minerals on carbon properties have led to this work; three principal topics were addressed; (1) the investigation of the solid state structure of biocarbons derived from various biomass feedstocks, (2) the removal of inorganic minerals from biomass, and (3) the investigation of biocarbon electronic structure subsequent to doping with select inorganic minerals. Charcoals and carbonized charcoals (i.e. biocarbons) were prepared from a wide variety of biomass substrates, including pure sugars containing 5- and 6-membered rings with furanose and pyranose configurations, lignin, agricultural residues (corncob and nut shells) and a hard wood. These biocarbons were subject to proximate and elemental analysis, gas sorption analysis, and analysis by ICP-MS, SEM, XRD, ESR, 13C CPMAS NMR, and MALDI-TOF MS. All the carbonized charcoals contained oxygen heteroatoms, had high surface areas, and were excellent conductors of electricity. Doping the biocarbon with boron or phosphorus resulted in a slight improvement in its electrical conductivity. The XRD analysis indicated that the carbonized charcoals possess an aromaticity of about 71% that results from graphite crystallites with an average size of about 20 . The NMR analysis confirmed the highly aromatic content of the carbonized charcoals. The ESR signals indicated two major types of carbon-centered organic radicals. A number of techniques employed highlighted differences between carbonized charcoals and synthetic graphite but none more so than MALDI-TOF spectrometry. The biocarbons contained readily desorbed discrete ions with m/z values of 701, 685, 465, 453, 429, and 317. All of the above findings were used to develop a model for the structure of carbonized charcoal that is consistent with the biocarbon's oxygen content, microporosity and surface area, electrical conductivity, radical content, and its MALDI-TOF spectra. The removal of inorganic mineral constituents from various biomass feedstocks was achieved via simple washing/soaking techniques using two different aqueous media; deionized water and citric acid. The most effective and consistent demineralization treatment for removing minerals from biomass involved a hot 0.1 molL-1 citric acid percolation treatment, ca. 67% of inorganic mineral matter was removed. Mineral matter at the levels present in typical biomass derived charcoals and carbons had no significant influence upon the surface area or the electrical resistivity in carbonaceous materials after high heat treatment (950 C).

Low grade heat (LGH) sources, here defined as below 80ºC, are one group of abundant energy sources that are under-utilised in the production of electricity. Industrial waste heat provides a convenient source of concentrated LGH, while solar ponds and geothermal resources are examples of sustainable sources of this energy. For a number of years RMIT has had two ongoing, parallel heat engine research projects aimed at the conversion of LGH into electricity. The Thermosyphon Rankine Engine (TSR) is a heat engine that uses water under considerable vacuum. The other research stream uses a hydrocarbon based working fluid in a heat engine employing the Trilateral Flash Cycle (TFC). The TSR Mk V was designed and built as a low cost heat engine for the conversion of LGH into electricity. Its main design advantages are its cost and the employment of only one moving part. Using the data gained from the experimental rig, deviations from the expected results (those derived theoretically) were explored to gain insight for further development. The results from the TSR rig were well below those expected from the design specifications. Although the experimental apparatus was able to process the required heat energy, the efficiency of conversion fell well below the expected 3% and was approximately 0.2%. The inefficiency was explained by a number of contributing factors, the major being form drag upon the rotor that contributed around 2/3 of the losses. Although this was the major cause of the power loss, other factors such as the interference with the rotor by the condensate on its return path contributed to the overall poor performance of the TSR Mk V. The RMIT TFC project came about from exploration of the available academic literature on the subject of LGH conversion. Early work by researchers into applying Carnot's theory to finite heat sources led them to explore the merits of sensible heat transfer combined with a cycle that passes a liquid (instead of a gas) though an expander. The results showed that it was theoretically possible to extract and convert more energy from a heat source of this type using this method than using any other alternative. This previous research was targeted at heat sources above 80ºC and so exploration of the theoretical and empirical results for sources below this temperature was needed. Computer models and an experimental rig using isopentane (with a 28ºC boiling point at atmospheric pressure) were produced to assess the outcomes of employing low temperature heat sources using a TFC. The experimental results from the TFC research proved promising with the efficiency of conversion ranging from 0.8% to 2.4%. Although s uch figures seem poor in isolation, it should be noted that the 2.4% efficiency represents an achievement of 47% of the theoretical ideal conversion efficiency in a rig that uses mainly off-the-shelf components. It also confirms that the TFC shows promise when applied to heat sources less than 80ºC.

La pyrolyse est la première étape de tout traitement thermique de la biomasse et conditionne la formation de gaz de synthèse pour la production d'électricité, d'hydrogène ou de carburants liquides. L'objectif de ces travaux est d'établir une relation entre la composition d'une biomasse et ses rendements en gaz de pyrolyse. Nous étudions la pyrolyse flash de façon expérimentale et fixons les conditions opératoires qui maximisent les quantités de gaz tout en visant un régime intrinsèque (particules d'environ 100 μm) : température de 950°C et temps de séjour d'environ 2 s. Puis nous tentons de développer un outil de prévision des rendements en gaz d'une biomasse quelconque en fonction de sa composition, applicable dans cette situation où l'équilibre thermodynamique n'est pas atteint. Nous montrons qu'une loi d'addition ne permet pas de corréler les rendements en gaz d'une biomasse avec les fractions massiques de cellulose, d'hémicellulose et de lignine contenues dans cette biomasse. Plusieurs explications sont proposées et investiguées une à une : différence de comportement pyrolytique d'un même composé selon la biomasse de laquelle il est extrait, interactions entre composés et influence de la matière minérale. En vue d'une application industrielle, nous étudions la pyrolyse de particules de tailles millimétrique et centimétrique, et réalisons une simulation numérique des réactions de reformage des gaz de pyrolyse. Cette simulation montre que le choix de la biomasse affecte largement les quantités de gaz de synthèse obtenues.

<p>Den här rapporten behandlar ett examensarbete där målet var att programmera en projektdatabas och projektöversikt åt Milton Medicinteknik KB. Syftet var att dess projektgrupper ska kunna komma åt att granska sina filer samt se filernas relationer med varandra, genom inloggning på en hemsida. Språken som användes var MySQL för att hantera databasen, PHP för att kommunicera mellan hemsidan och webbservern, HTML för att formatera webbsidorna och ActionScript 3 som är Flash programmeringsspråk för att programmera projektöversikten.</p><p> </p><p>I huvuddelen av rapporten är det beskrivet hur projektöversikten och projektdatabasen fungerar. Från hemsidan kan man ladda upp filer som hanteras av projektgrupper och användare med rätt rättigheter. Det finns tre typer av behörighet som användarna kan ha: Administratör som kan skapa användare och projektgrupper, projektledare som ansvarar för sin egen projektgrupp samt vanliga användare som endast kan ladda upp och länka filer i sin egen projektgrupp. Projektöversikten tillåter att användarna på ett överskådligt sätt kan se hur filerna som de har rättighet att se är länkade med varandra, lägga till och ta bort egna filer samt se deras innehåll.</p>

<p>Denna rapport beskriver och undersöker olika sätt att använda online 3D i webbpresentationer. 3D ställs emot vad som ibland brukar kallas 2,5D (Man fotograferar en produkt ur olika vinklar för att få en serie med bilder som kan ge en fiktiv 3D upplevelse). Rapporten ger bakgrund och historia över online 3D teknologi, ger en översikt över marknaden för online produktpresentationer idag och försöker ge en ögonblicksbild av situationen i andra kvartalet 2007 över en snabb föränderlig marknad. Fyra olika 3D system ställs mot varandra med hjälp av praktiska kodexempel och avslutas med en helhetslösning för dynamisk generering av webbsidor. Målgruppen är programmerare och webbutvecklare som tar fram material för små och medelstora företag.</p>

We enhance photographs shot in dark environments by combining a picture taken with the available light and one taken with the flash. We preserve the ambiance of the original lighting and insert the sharpness from the flash image. We use the bilateral filter to decompose the images into detail and large scale. We reconstruct the image using the large scale of the available lighting and the detail of the flash. We detect and correct flash shadows. This combines the advantages of available illumination and flash photography. / Singapore-MIT Alliance (SMA)