Dissertations / Theses on the topic 'Smoldering'

An experimental study has been carried out to investigate the effects of buoyancy on smoldering of polyurethane foam. The experiments are conducted with a high void fraction flexible polyurethane foam as fuel and air as oxidizer, in a geometry that approximately produces a one dimensional smolder propagation. The potential effect of buoyancy in the process is analyzed by comparing upward and downward smolder propagation through a series of normal gravity and variable gravity experiments. Both opposed and forward mixed (free and forced) flow smolder configurations are studied. In opposed smolder the oxidizer flow opposes the direction of smolder propagation, and in forward smolder both move in the same direction. Variable gravity free flow tests are also conducted in an aircraft flying a parabolic trajectories that provides low gravity periods of up to 25 sec. Measurements are performed of the smolder reaction propagation velocity and temperature as a function of the location in the sample interior, the foam and air initial temperature, the direction of propagation and the air flow velocity. This information is used in conjunction with previously developed smolder theoretical models to determine the smolder controlling mechanisms and the effect of gravity. Three zones in the fuel sample with clearly defined smolder characteristics are identified. A zone close to the igniter where smolder is affected by the external heat, a zone at the end of the sample where smolder is affected by the environment, and a zone at the end of the sample where smolder is affected by the environment, and a zone, in the middle of the foam, that is free from external effects. This last zone is the most characteristic of one dimensional, self-supported smolder, and the one that is studied in greater detail. In mixed flow convection buoyancy induced flows together with the forced flow are the primary mechanism of oxidizer transport to the reaction zone, while diffusion has a secondary importance. In natural convection, downward smoldering is of the opposed type while upward smoldering resembles more the forward type. For opposed flow smoldering, both natural and forced, the smolder propagation velocity is found to increase with the oxidizer mass flux reaching the reaction zone. This result confirms predictions from previously developed theoretical models that the smolder velocity is proportional to the oxygen mass flow. The experimental data is correlated in terms of a non-dimensional smolder velocity derived from these models, the results show very good agreement between theory and experiments for strong smolder. To implement the models, an analysis of the gas flow field is developed where the effect of significantly different permeabilities between char and foam is been Extinction is observed for very low and for very high flow rates, which shows that smolder is controlled by a sensitive competition between oxygen supply and heat losses to and from the reaction zone. Under these conditions the models do not describe the experiments well. The forward flow smolder experiments show that forward smoldering is controlled not only by the competition between oxygen supply and heat losses to and from the reaction zone but also by the competition between pyrolysis and oxidation. For low flow velocities a regime resembling the opposed flow is observed. As the air flow velocity is increased, foam pyrolysis followed by char oxidation is the controlling smolder mechanism. For both these conditions the theoretical models describe the experiments well. Increasing the flow velocity further results in a smolder propagation velocity controlled by total fuel consumption, in downward burining. For upward burning transition to flaming is observed for very high air flow velocities. This last regime is not well predicted by the theoretical models. The results from the experiments in variable gravity environment conducted in the KC-135A and Leajet airplanes confirm the normal gravity observations that the competition between heat losses and oxidizer transport is the major mechanism controlling smolder. The absence of convective flow in low gravity results in higher temperature in the unburnt fuel and char due to smaller heat losses to the surroundings. However, the oxidizer transport to the reaction zone also decreases and as a result the temperature at the reaction zone decreases indicating a weakening of the eaction, The presence of pyrolytic reactions in foward smolder and their capability to inhibit smoldering complicates the above described smolder mechanisms.

After World War II, state-sponsored deportations amounting to ethnic cleansing occurred and showed that the roots of the Czech-German cultural competition are important. In Bohemia, Czechs and Germans share a long history of contact, both mutually beneficial and antagonistic. Bohemia became one of the most important constituent realms of the Holy Roman Empire, bringing Czechs into close contact with Germans. During the reign of Václav IV, a theologian at the University of Prague named Jan Hus began to cause controversy. Hus began to preach the doctrines outlined by the Englishman John Wycliffe. At the Council of Constance church officials sought to stamp out Wycliffism and as part of that effort summoned Hus, convicted him of heresy and burned him at the stake on July 6, 1415. Bohemia rose in rebellion, in what became the Hussite Wars. Bohemians elected a Hussite king, George of Poděbrady. Shortly after his death, the Thirty Years War began and resulted in the Austrian Habsburgs gaining the throne of Bohemia. The Habsburg dynasty suppressed Protestantism in the Czech lands and ushering in a brutal Counter-Reformation and forced reconversion to Catholicism. By the nineteenth century, a revival of Czech culture and language brought about Czech nationalism. Spurred by the nobility’s desire to regain lost power from the monarchy, a distinct Czech culture began to coalesce. With noble patronage, Czech nationalists established many of the symbols of the Czech nation such as the Bohemian Museum and the National Theater and initiated Czech language instruction at Charles University in Prague and finally a separate Czech university in Prague. The first generation of nationalist Czech leaders, lead by František Palacký, gave way to a newer generation of nationalists, lead eventually by Tomáš Garrigue Masaryk. Masaryk, a professor at the university, successfully lead the efforts during World War I to create an independent Czechoslovakia. Masaryk’s decades-long debate with historian Josef Pekař over the meaning of Czech history illustrates how Czech nationalists distorted historical facts to fit their nationalist ideology. The nationalists succeeded in gaining independence, but faced unsuccessfully forged a new state with a significant, but problematic, German minority.

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Tecnologias avançadas para a geração de energia usando combustíveis não convencionais xisto betuminoso e seu semi-coque, areias betuminosas, petróleo extra-pesado e biomassa proveniente de resíduos sólidos urbanos e de lodo de esgoto - têm em comum processos termoquímicos compostos de complexas reações químicas. Este trabalho trata da formulação e otimização de mecanismos químicos normalmente envolvidos na pirólise do xisto betuminoso e na combustão do xisto betuminoso e seu semi-coque. Problemas inversos (usando o algoritmo de Levenberg-Marquardt) foram empregados para minimizar o erro entre os valores estimados e os dados de termogravimétria para os mecanismos de reação de 3 passos para a pirólise do xisto betuminos, e mecanismos de 4 e 3 passos para o xisto betuminoso e seu semi-coque, respectivamente. Os parâmetros cinéticos, tais como ordem de reação, fator pré-exponencial, energia de ativação e os coeficientes estequiométricos que afetam a secagem, as reações de oxidação, pirólise e descarbonatação foram estimadas com sucesso. Além disso, os erros estatísticos e residuais foram avaliados, resultando em um valor razoável para todas as estimativas e o mecanismo cinético proposto e estimado para a combustão do semi-coque foi aplicado em um código em meios porosos. Um estudo paramétrico entre o perfil de temperatura e a velocidade do ar, e o perfil de temperatura e a concentração de carbono fixo foi desenvolvido. Este estudo mostra que o perfil de temperatura é extremamente influenciado por estes parâmetros, confirmando que a propagação da frente é controlada pela injeção de O2. Palavras-chave: Xisto Betuminoso, Semi-Coque, Pirólise, Combustão, Estimação de Parâmetros, Problemas Inversos, Levenberg-Marquardt, Meios Porosos.

Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2002.
Includes bibliographical references (leaves 154-166). Also available in electronic version. Access restricted to campus users.

A MATLAB model was developed for the smoldering combustion of wastewater in the context of a decentralized residential wastewater treatment appliance. Data from a batch process sewage smoldering experiment was simulated using implicit finite-difference approximations, assuming one-dimensional transient conductive heat transfer. The time-dependent temperature profiles within the column represented the main parameters of interest and were used to verify recoverable heat energy estimations. Given that the modeling method used for this thesis represents a unique approach, the assumptions and limitations of this model are thoroughly described in the context of reproducing results for other smoldering setups. A lack of convergence is seen in the model validation section of this report. Consequently, the practicality of this particular model contains significant limitations. Theoretical applications are also discussed and analyzed in terms of comparisons to modern alternatives and prototype feasibility.

A computational study has been carried out to investigate smoldering ignition and propagation in polyurethane foam. The onedimensional, transient, governing equations for smoldering combustion in a porous fuel are solved accounting for improved solid-phase chemical kinetics. A systematic methodology for the determination of solid-phase kinetics suitable for numerical models has been developed and applied to the simulation of smoldering combustion. This methodology consists in the correlation of a mathematical representation of a reaction mechanism with data from previous thermogravimetric experiments. Geneticalgorithm and trail-and-error techniques are used as the optimization procedures. The corresponding kinetic parameters for two different mechanisms of polyurethane foam smoldering kinetics are quantified: a previously proposed 3-step mechanism and a new 5-step mechanism. These kinetic mechanisms are used to model one-dimensionalsmoldering combustion, numerically solving for the solid-phase and gasphase conservation equations in microgravity with a forced flow of oxidizer gas. The results from previously conducted microgravity experiments with flexible polyurethane foam are used for calibration and testing of the model predictive capabilities. Both forward and opposed smoldering configurations are examined. The model describes well both opposed and forward propagation. Specifically, the model predicts the reaction-front thermal and species structure, the onset of smoldering ignition, and the propagation rate. The model results reproduce the most important features of the smolder process and represent a significant step forward in smoldering combustion modeling.

La gazéification étagée est une technologie innovante pour la production d’énergie renouvelable de petite et moyenne puissances, pour laquelle l'élargissement de la gamme de biomasses utilisables constitue un enjeu majeur de développement. Cette thèse porte spécifiquement sur la pyrolyse oxydante en lit fixe, première étape clé du procédé, qui conditionne fortement la performance et la fiabilité de cette technologie. Trois types de biomasses – pin, miscanthus, et paille – conditionnées sous forme de granulés ont été étudiés. Une étude expérimentale a été réalisée sur un réacteur pilote à lit fixe de 20 cm de diamètre et 1.6 m de hauteur permettant de reproduire des conditions opératoires proches de celles rencontrées durant l'étape de pyrolyse dans les gazéifieurs industriels. Le fonctionnement du procédé pour les trois biomasses a été caractérisé par la mesure du ratio air/biomasse, des températures, des rendements en charbon, gaz permanents et condensables et de leurs compositions. Une attention particulière a été portée à la zone d'oxydation qui se propage verticalement vers le haut dans le lit de biomasse. Une méthodologie a été développée pour mesurer la vitesse de propagation, l'épaisseur et le tassement de cette zone et étudier l'impact de la nature de la biomasse. Dans un lit de granulés de bois, la vitesse et l'épaisseur de la zone d'oxydation est 25 % plus faible que dans un lit de granulés de paille ou miscanthus. L'effet catalytique des matières minérales sur les réactions de pyrolyse primaire et secondaire et son impact sur le fonctionnement du procédé, ont également été mis en évidence
Staged gasification is an innovative technology for small and medium renewable energy production. The expansion of the range of usable biomass remains a major obstacle to development. This thesis focuses specifically on the oxidative pyrolysis in a fixed bed, the first step of the process that strongly influences the performance and reliability of this technology. Three types of biomass- pine, miscanthus and wheat straw - in form of pellets were studied. An experimental study was carried out in a pilot fixed bed reactor of 20 cm diameter and 1.6 m height allowing the reproduction of similar conditions to those existing in the pyrolysis step of an industrial gasifier. The process operation for the three biomasses was characterized by measuring the air/biomass ratio, bed temperature, yields and compositions of char, permanent gases and condensates. A particular attention was paid on the oxidation zone which propagates upward towards the raw biomass. A method was developed to measure the propagation velocity, thickness and the compaction of the oxidation zone and to study the impact of the biomass nature. Velocity and thickness of this zone were 25 % lower in a fixed bed of wood pellets than in beds of wheat straw or miscanthus. Catalytic effect of the mineral matters on primary and secondary pyrolysis reactions and their impact on the process operation have been highlighted

Forested peatlands of the Great Dismal Swamp (GDS) have been greatly altered since colonial times, motivating recent restoration efforts. Community structure and function were hydrologically altered by 19th and 20th century ditches installed to lower water levels and enable early timber harvesting. Contemporary forest communities are comprised of maturing remnants from selective timber harvesting that ended in the early 1970s. Red maple (Acer rubrum) has become the dominant species across GDS, encroaching on or replacing the historical mosaic of cypress (Taxodium spp.)/tupelo (Nyssa spp.), Atlantic white-cedar (Chamaecyparis thyoides), and pocosin (Pinus spp.). Moreover, peat soil has been exposed to more unsaturated conditions resulting in carbon loss through decomposition and increased peat fire frequency and severity. Installation of ditch control structures aim to control drainage and re-establish historical hydrology, vegetation communities, peat accretion rates, and fire regime. To help inform restoration and management, we conducted two complimentary studies to test hypotheses regarding hydrologic influences on vegetation, peat depths, and peat fire vulnerability. First, we found thicker peat, lower maple importance, and higher species richness at wetter sites (e.g., higher mean water levels). In our second study, we evaluated the integrated effects of peat properties and water level dynamics on peat fire vulnerability. We found decreased burn vulnerability with increased wetness, suggesting that the driest sites were always at risk to burn, whereas the wettest sites never approached fire risk conditions. Together our findings demonstrate strong hydrologic controls on GDS ecosystem structure and function, thereby informing water level management for restoration goals.
Master of Science

La thèse s’intéresse au contrôle de la température d’un front de combustion propagé dans un milieu poreux contenant du carbone fixe et des carbonates (CaCO3). L’objectif principal est de réduire la température, in situ (récupération d’huile ou production de gaz à partir d’un schiste bitumineux) ou dans un procédé (combustion de semicoke), afin de limiter la décarbonatation du milieu et les émissions induites de CO2. Le milieu réactif retenu pour réaliser les expériences en laboratoire est un schiste bitumineux préalablement broyé (0.5 à 2 mm) et pré-pyrolysé, appelé semicoke. Le front est propagé en co-courant. La première technique testée expérimentalement est l’ajout au semicoke d’un matériaux inerte (sable) et/ou d’un matériaux réactif (CaCO3) afin de faire varier le taux de carbone fixe et le taux de CaCO3 et ceci indépendamment. Nous montrons que l’augmentation de CaCO3 permet de baisser la température à 800 °C, mais pas en dessous, ce qui ne permet pas d’éviter la décarbonatation. Faire chuter le contenu en carbone fixe permet de baisser la température du front, voire d’atteindre l’extinction. Aux températures de propagation les plus basses, la décarbonatation est fortement limitée. En revanche le front ralentit car il n’utilise plus tout l’oxygène alimenté. La deuxième technique originale consiste à ajouter du CO2 (20 %molaire) dans l’air de combustion. Nous montrons que dans le cas d’un front chaud, ceci permet de réduire le taux de décarbonatation de 100% à 70%, et d’augmenter en parallèle la production de CO résultant de l’oxydation du carbone fixe, ce qui augmente le PCI du gaz produit. Sur un front plus froid, la décarbonatation qui était de 20% est totalement évitée par l’ajout de CO2. Enfin, des expériences sont proposées dans le mode de combustion “reaction trailing”, très peu connu et mis en oeuvre. Ce mode a l’intérêt majeur d’éviter les réactions de “Lower Temperature Oxidation” préjudiciables au rendement en huile ou en gaz d’un process in situ. Des expériences stables et répétables sont réalisées avec différents pourcentages d’oxygène dans le gaz alimenté. La température du front est directement liée à ce paramètre ; la décarbonatation est clairement limitée dans ce mode de propagation. Deux types de modélisation sont proposés. Un bilan de matière et d’énergie basé sur des expressions analytiques simples permet d’évaluer la température du front et sa vitesse de propagation. Un modèle numérique développé par l’IMFT se base sur des équations de transfert convectif/diffusif de chaleur et de matière, couplées aux réactions d’oxydation du carbone (en CO et en CO2) et de décarbonatation de CaCO3. Il décrit de façon très satisfaisante les expériences en mode “reaction leading” avec variation de la composition du milieu (première technique)
This PhD thesis focuses on the control of the smoldering front propagating in a porous medium containing fixed carbon and carbonates (CaCO3). The main objective is to reduce the front temperature, in situ (oil recovery or gas production from oil shale) or in process (combustion of semicoke), in order to limit the medium decarbonation and the resulting CO2 emissions. The reactive porous medium retained to realize the laboratory experiments is a crushed (0.5 to 2 mm) and pre-pyrolyed oil shale, called semicoke. The front propagates in co-current. The first technique experimentally tested is the addition to the semicoke of an inert material (sand) and/or a reactive material (CaCO3) to vary the contents of fixed carbon and of CaCO3, independently. We show that the increase of the CaCO3 content enables to reduce the temperature to 800 °C, but not below; this does not allow to avoid decarbonation. Bringing down the fixed carbon content enables to reduce the front temperature, see even to reach extinction. In the lowest temperatures of propagation, the decarbonation is strongly limited. On the other hand, the front slows down because it does not use all of the fed oxygen. The second original technique consists in adding CO2 (20 mol.%) to the oxidizer air. We show that for a hot front, the decarbonated fraction is reduced from 100% down to 70%, and the CO production at fixed carbon oxidation is increased; this leads to increase the LCV of the produced gas. For a cold front, the decarbonation which was 20%, is totally avoided by adding CO2. Finely, experiments are proposed in the “reaction trailing” combustion mode, little known and implemented. This mode has the major interest to avoid the reactions of “Lower Temperature Oxidation” prejudicial for oil or gas yields in in situ process. Stable and repeatable experiments are realized with different oxygen fractions in feeding gas. The front temperature is directly linked to this parameter; the decarbonation is clearly limited in this mode of propagation. Two types of modeling are proposed. A mass and thermal balance based on simple analytical expressions enables to evaluate the front temperature and velocity. A numerical model developed by IMFT is based on convective/diffusive heat and mass transfer equations coupled with the oxidation reactions (into CO and CO2) and CaCO3 decarbonation is proposed. It describes in a very satisfactory way the experiments in the “reaction leading” mode with variation of the medium composition (first technique)

An accurate estimation of biomass burning emissions is in part limited by the lack of knowledge of fire burning phase (smoldering/flaming). In recent years, several fire detection products have been developed to provide information of fire radiative power (FRP), location, size, and temperature of fire pixels, but no information regarding fire burning phase is retrieved. The Day-Night band (DNB) aboard Visible Infrared Imaging Radiometer Suite (VIIRS) is sensitive to visible light from flaming fires in the night. In contrast, VIIRS 4 µm moderate resolution band #13 (M13), though capable to detect fires at all phases, has no direct sensitivity for discerning fire phase. However, the hybrid usage of VIIRS DNB and M-bands data is hampered due to their different scanning technology and spatial resolution. In this study, we present a novel method to rapidly and accurately resample DNB pixel radiances to M-band pixels’ footprint that is based on DNB and M-band’s respective characteristics in their onboard schemes for detector aggregation and bow-tie effect removals. Subsequently, the visible energy fraction (VEF) as an indicator of fire burning phase is introduced and is calculated as the ratio of visible light power (VLP) and FRP for each fire pixel retrieved from VIIRS 750 m active fire product. A global distribution of VEF values, and thereby the fire phase, is quantitatively obtained, showing mostly smoldering wildfires such as peatland fires (with smaller VEF values) in Indonesia, flaming wildfires (with larger VEF values) over grasslands and savannahs in sub-Sahel region, and gas fares with largest VEF values in the Middle East. VEF is highly correlated with modified combustion efficiency (MCE) for different land cover types or regions. These results together with a case study of the 2018 California Campfire show that the VEF has the potential to be an indicator of fire combustion phase for each fire pixel, appropriate for estimating emission factors at the satellite pixel level.

Skogsbränder utgör ett stort problem både lokalt, regionalt och globalt. De förstör stora värden, frigör stora mängder kol ut i atmosfären och är mycket resurskrävande att bekämpa. Under markytan kan glödbränder fortsätta långt efter att flambranden ovan mark är släckt. Glödbränder brinner mycket långsammare än de öppna flambränderna, men är istället svårare att upptäcka och ställer andra krav vid bekämpning. En typ av glödbrand som kan påträffas i skogsbränder är torvbränder. Det är glödbränder som uppstår i torvmarker som utsatts för torka. Branden äter sig sakta igenom torven och kan gå djupt ner i marken. Svårigheter med att lokalisera bränderna och att få ner tillräckligt med vatten i de djupare torvlagerna gör dem svåra att släcka. Idag används ofta dimspikar, även kallade jordspett, för att släcka bränder som gått ner under markytan. På vissa ställen har även skärsläckaren börjat användas. Detta arbete syftar till att ge en bättre förståelse för de två verktygens funktion och effektivitet vid släckarbete av torvbränder. För att göra det har två tester genomförts på Luleå räddningstjänsts övningsfält, ett för dimspik och ett för skärsläckare. En försöksuppställning byggdes upp med en invändig tvärsnittsarea på 80×80 cm och en höjd på 1,1 m. Den fylldes sedan med torv som packades lätt tills torvlagret var 1 m tjockt. Det som undersöktes var verktygens penetreringstid för vattnet att nå 1 m ner i torven samt hur stor spridning vattnet fick över tvärsnittsarean på djupet 1 m. Båda verktygen hade liknande flöden (56 l/min för skärsläckaren och 58 l/min för dimspiken) så de uppmätta skillnaderna i resultat berodde på hur vattnet transporterades, inte på mängden vatten. Skärsläckaren slog igenom på cirka 1 sekund och bildade ett utgångshål på cirka 1 dm2, där det var blött ytterliga någon centimeter runtomkring för en total våt area på cirka 2 dm2. Testet avslutades efter 30 sekunder då ingen förändring kunde ses i storleken på utgångshålet och den våta arean från efter de första få sekunderna. Vattnet sprutade rakt igenom torven. Dimspiken vätte igenom efter 26 sekunder och den våta arean växte kontinuerligt. Inget utgångshål bildades i detta fall. När dimspiken stängdes av efter 1 minut och 45 sekunder, så hade cirka 32 dm2 blivit blött; vilket motsvarar ungefär halva tvärsnittarean hos försöksuppställningen. Spridning fortsatte efter att dimspiken slagits av och nästan hela tvärsnittsarean var blöt efter ytterligare några minuter. Skärsläckaren hade en mycket snabb penetreringstid, men sprutade istället mycket vatten rakt igenom torven, vilket medförde att stora mängder vatten passerade genom torven utan att väta en stor yta eller volym. Dimspiken hade en mycket längre penetreringstid, i gengäld så sköts inte vattnet rakt igenom torven utan spred ut sig och vätte en större yta. Båda verktygen har sina för- och nackdelar. Vilket verktyg som är bäst är väldigt situationsberoende. Skärsläckaren har bland annat snabbare penetreringstid och möjliggör fler snabba ingrepp, medan dimspiken täcker en större area per angreppspunkt och är lättare och säkrare att hantera.
Wildfires are a major problem both locally, regionally and globally. They destroy large values, emit large quantities of carbon into the atmosphere and are very resource intensive to fight. Smoldering fires can continue under the ground surface long after the flaming fire above ground is put out. Smoldering fires burn much slower than the flaming fires, but in turn they are harder to discover and require different means to fight. Peat fire is one type of smoldering fire that can be found in wildfires. It is a smoldering fire that occur in peatlands exposed to drought. The fire slowly eats its way through the peat and can go deep into the ground. Difficulty locating them and getting enough water into the deeper peat layers makes them difficult to extinguish. Today, fognails are often used to extinguish smoldering fires in the ground. The cutting extinguisher is another tool that has been used to fight smoldering fires in the ground in some cases. This bachelor thesis aims to provide a better understanding of the function and efficiency of the two tools in extinguishing peat fires. To do this, two tests have been carried out on the fire department’s training field in Luleå, one with a fognail and one with a cutting extinguisher. A test stand was constructed with an internal cross-sectional area of ​​80×80 cm and a height of 1.1 m. It was then filled with peat which was lightly packed until the peat layer was 1 m thick. What was investigated was the tools’ penetration time for the water to reach 1 m down into the peat and the size of the water spread over the cross-sectional area at the depth of 1 m. Both tools had similar flows (56 l/min for the cutter extinguisher and 58 l/min for the fognail) so the differences arose in how that water was used, not the amount of water. The cutting extinguisher broke through in about 1 second and formed an exit hole of about 1 dm2 with additional wetness of a few centimeters around for a total wet area of ​​about 2 dm2. The test was terminated after 30 seconds when no change could be seen in the size of the output hole or the wet area from after the first few seconds. The water sprayed right through the peat. The water from the fognail got through after 26 seconds and the wet area grew continuously. No exit hole was formed in this case. When the fognail was turned off after 1 minute and 45 seconds, about 32 dm2 had become wet, which corresponds to about half the cross-sectional area of the test stand. However, spreading continued despite the fognail being turned off and almost the entire cross-sectional area was wet after a few more minutes. The cutting extinguisher had a very fast penetration time, but as a result it sprayed a lot of water right through the peat without wetting a large area or volume. The fognail had a much longer penetration time, but in return, the water was not shot straight through the peat, but spread out and wet a larger surface. Both tools have their advantages and disadvantages. Which tool is the best depends a lot on the situation. The cutting extinguisher has, among other things, a faster penetration time and allows for more rapid interventions, while the fog nail covers a larger area per attack point and is easier and safer to handle.

Deux vaccins sont actuellement disponibles pour la prévention des infections invasives à pneumocoques (IIP) : un vaccin polysaccharidique Pneumovax® (PPV23) et un vaccin conjugué Prevenar13® (PCV13), induisant respectivement une protection contre 23 et 13 sérotypes. Le PPV23 est considéré comme faiblement immunogène, en particulier chez les personnes âgées et les patients immunodéprimés. Le PCV13, en revanche, en raison de la conjugaison à une protéine porteuse, présente l'avantage d'induire une réponse immunitaire T-dépendante, non observée avec le vaccin PPV23. Dans notre travail nous avons donc évalué l'impact des stratégies vaccinales utilisant le PCV13 et le PPV23 sur différentes populations de patients à risque. Dans une première étude, nos résultats sur la vaccination anti-pneumococcique chez des patients atteints de myélome indolent (SMM) ont montré qu'une dose de PCV13 seul, induisait une réponse immune transitoire et de faible persistance. Ces résultats suggéraient l'utilisation d'un schéma vaccinal incluant plusieurs doses de PCV13 ou une association avec le PPV23. Depuis 2013, ce schéma combiné du PCV13 et du PPV23 est le schéma recommandé par la Haute Autorité de Santé en France chez les patients à risque, avec les délais suivants : une dose de PCV13 suivie d'une dose de PPV23, 8 semaines après. Nous avons par la suite étudié cette stratégie vaccinale combinée chez des patients à risque d'IIP : patients atteints de lupus érythémateux systémique (SLE) et patients atteints de polyarthrite rhumatoïde (PR). Nos résultats montrent une immunogénicité à court terme de la stratégie combinée, mais une protection qui ne persiste pas au-delà de deux ans. De façon surprenante, les taux d'anticorps 2 ans après la vaccination, sont inférieurs aux taux pré-vaccinaux pour les patients PR. Cet effet délétère du PPV23 sur la réponse vaccinale induite par le PCV13 est appelé hyporéponse. Ce phénomène, observé chez les patients PR, ne se retrouve pas chez les patients SLE dont la vaccination PPV23 a été effectuée plus à distance du PCV13. Ces résultats suggèrent que le schéma vaccinal plus tardif (c'est-à-dire une vaccination par le PPV23 six mois après le PCV13 au lieu de deux mois) inhiberait le phénomène d'hyporéponse. Dans une troisième partie, nous avons comparé différents schéma vaccinaux modulant les doses des vaccins et les délais d'injection chez des volontaires sains mais également dans un modèle murin d'hyporéponse développé au sein du laboratoire. Notre hypothèse était que la modulation du schéma vaccinal utilisant les 2 vaccins pouvait à la fois induire une protection à long terme et prévenir l'hyporéponse. Nos résultats ont montré que l'utilisation d'une dose diminuée de PPV23 ou l'injection concomitante des deux vaccins n'empêchaient pas l'hyporéponse. En revanche, en allongeant le délai entre le PCV13 et le PPV23, le phénomène d'hyporéponse est limité. Des études cliniques chez les patients à risque d'IIP sont nécessaires afin d'évaluer une stratégie combinée tardive, où le PPV23 serait reçu au moins 6 à 12 mois après le PCV13
Two vaccines are currently available for the prevention of invasive pneumococcal diseases (IPD): a polysaccharide vaccine, Pneumovax® (PPV23) and a conjugate vaccine, Prevenar13® (PCV13), inducing protection against 23 and 13 serotypes, respectively. PPV23 is considered to be weakly immunogenic, particularly in the elderly and immunocompromised patients. PCV13, however, due to the conjugation to a carrier protein, has the advantage of inducing a T-dependent immune response, not observed with PPV23 vaccine. In our work, we therefore evaluated the impact of vaccine strategies using PCV13 and PPV23 on different populations of patients at risk of IPD. In a first study, our results on anti-pneumococcal vaccination in patients with smoldering myeloma (SMM) showed that a single dose of PCV13 induces a transient immune response and long term persistence. These results suggested the use of a vaccination schedule including several doses of PCV13 or association with the PPV23. Since 2013, this combined strategy of PCV13 and PPV23 is recommended by la Haute Autorité de Santé (HAS) for patients at risk, with the following delays: a dose of PCV13 followed by a dose of PPV23, 8 weeks later. We then studied this combined vaccine strategy in patients at risk of IPD: patients with systemic lupus erythematosus (SLE) and patients with rheumatoid arthritis (RA). Our results show a short-term immunogenicity of the combined strategy, but a protection that does not persist beyond two years. Surprisingly, antibody levels 2 years after vaccination are lower than pre-vaccine levels for RA patients. This negative effect of PPV23 on PCV13-induced immune response is called hyporesponsiveness. This phenomenon, observed in RA patients, is not found in SLE patients who received PPV23 vaccination at distance from PCV13. These results suggest that the delayed vaccination schedule (ie, PPV23 vaccination six months after PCV13 instead of two months) could inhibit the hyporesponsiveness phenomenon. In a third study, we compared different vaccine strategies modulating vaccine doses and injection times in healthy volunteers but also in a mouse model of hyporesponsiveness developed in our laboratory. Our hypothesis was that modulation of the vaccine schedule using both vaccines could both induce long-term protection and prevent hyporesponsiveness. Our results showed that decreased doses of PPV23 or concomitant injection of both vaccines did not prevent hyporesponsiveness. However, by increasing the delay between PCV13 and PPV23, the phenomenon of hyporesponsiveness is limited. Clinical studies in patients at risk of IPD are needed to evaluate a delayed combined strategy, where PPV23 would be received at least 6 to 12 months after PCV13

This report is a study on the smoldering combustion of natural sawdust from untreated woods. The objective was to develop and test an experimental technique to study the fundamental behavior of sawdust smolder. The experimental setup was an annulus cookstove packed with sawdust between the inner and outer radii creating a central hollow core. The sawdust was ignited by a heating coil wrapped around the inner radius. Thermocouples were embedded in the sawdust bed fanning out in the radial direction, and temperature was recorded throughout the smolder process. Consistent with the literature, the experimental results indicate that wood smolder consists of three pathways, 1) sawdust to char, 2) sawdust to volatiles, and 3) char to ash. Pathways 1 and 3 can be clearly characterized by the temperature profile of the smolder; however, pathway 2 often involves flaming of the sawdust and is beyond the scope of this study. Pathway 1, sawdust to char, is an endothermic reaction that results in a clearly defined char front that propagates across the sawdust bed in the radial direction. As smolder proceeds, the char continues to oxidize and breaks down into non-volatile products such as water vapor and carbon dioxide (CO₂) in further exothermic reactions. Pathway 2, char to ash, is an exothermic reaction that can lead to glowing combustion when exposed to sufficient amounts of oxygen and results in spikes in temperature. In contrast to the clearly defined char front, the ashing zone traces cracks in the sawdust where air can penetrate through, and has no discernible front. Section 1 discusses the motivation behind the study of sawdust cookstoves in third world countries, in particular Ghana, to replace wood with sawdust as a cheap alternative for household fuel. Section 2 details the experimental setup of the cookstove rig and the methodology of the experiments conducted. Section 3 reports the results of the experiments and analyzes the temperature profiles in relation to the three types of chemical reactions as noted above. Section 4 concludes with a summary of the results and discusses efforts in measuring emissions from the smolder and future work to be done.
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A growing number of research studies conclude that exposure to environmental tobacco smoke (ETS) has an overwhelming effect on the health of children causing 400,000 episodes of childhood sickness each year in Canada. The home is the predominant site of exposure, and maternal smoking is a primary source of ETS exposure in young children. Little is known or reported about maternal efforts to protect children from ETS. This situation poses a challenge to find ways to assist women in protecting their children from ETS. The purpose of this grounded theory study was to describe the process women use to protect their children from ETS. Open-ended interviews were conducted with nine mothers who smoked or were in contact with people who smoked. The findings of this study indicated that protecting children from ETS was a complex three-phase process that involved "avoiding the judgemental gaze". In the first phase, starting out with good intentions, the women established rules to protect their children from ETS and projected themselves as "good mothers". The rules were successfully applied but in the course of everyday life, circumstances presented that tested and sometimes weakened the women's resolve to abide by their rules. In the second phase, making exceptions, rules were revised to accommodate frequently occurring transgressions or replaced with less, restrictive guidelines to appease others' needs to smoke and to be "socially acceptable". The new rules were a significant departure from the women's initial good intentions creating contradictions that they could not ignore. In the third phase, dealing with contradictions, the women used several strategies to manage the dissonance they experienced as a result of their transgressions: seeking agreement from others, minimizing the effects of ETS, hiding their smoking, ignoring health information, explaining addiction, and living in hope. The process described in this study extends our understanding of how women protect their children from ETS and provides some directions for supporting women in the challenges and difficulties they encounter.

碩士
國立高雄第一科技大學
環境與安全衛生工程研究所
103
Bisphenol A (BPA) is an important raw material which is widely used for manufacturing polycarbonate and epoxy resins. Its melting point is 158~159?aC and thus is stored as solid powder or molten liquid at elevated temperature. However, there has been an incident occurring from BPA powder leaking into the fiberglass wool used for insulation in high temperature vessel and then BPA smoldering occurred in the fiberglass wool leading to a fire. Thus, it is important to study the mechanism and condition of BPA smoldering in fiberglass wool. This study followed the work of You (2014) in which the oven basket method was used to study the smoldering of BPA impregnated in fiberglass wool under different temperature. The BPA/fiberglass wool weight ratio was raised to a maximum of 5 and the volume of the box frame and fiberglass wool was increased 27 times. The oven basket method was performed under different temperature and BPA content. A smoldering model was developed to include temperature, BPA content, and activation energy for smoldering.

碩士
東方設計學院
文化創意設計研究所
102
Smoldering has been one of the oldest ways in pottery production. In the flame process, carbon black smokes generated from fuel combustions scent a pottery body, which results in a blackened body surface texture of native flavor. The way that Taiwan Paiwan aborigines fired clay pots exemplifies the smoldering manner. It leaves direct fire burning or blackened traces of carbon characteristics in the body, bringing people mysterious and warm feeling, which is the most traditional way of pottery. Nevertheless, the black clay pottery, one of the Paiwan’s three treasure crafts, cannot be made at smoldering temperature firing. As a result, it has no practical function in use but survives only in the decorative market. The focus of this study is to explore how to improve the smoldering techniques, and the development of energy storage practicality smoked pottery. We will strive to advance the firing technology on the material nature, combined with a creative design, such that both "technical" and "design" can be improved in the pottery production at the same time. Subsequently, the black clay totems can be increasingly used in many aspects. This effort will ensure that the black clay pots turn into a sustainable industry in the Paiwan’s craft culture.