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Impact du délai de livraison sur le niveau de stock : une approche basée sur la méthode IPA / Impact of delivery time on buffer level : an approach based on IPA methodTurki, Sadok 07 December 2010 (has links)
Le monde industriel actuel ne cesse pas d'évoluer. La concurrence accrue, la grande diversification des produits demandés, le développement du commerce électronique, l'augmentation des échanges de données entre donneurs d'ordres et le producteur, sont autant de facteurs qui poussent les entreprises à continuellement optimiser leurs systèmes de production afin de produire et de livrer dans des délais précis, à des coûts réduits, en satisfaisant des niveaux de service élevés exigés par les clients. Ceci nécessite l'utilisation de méthodes bien adaptées pouvant guider le concepteur dans les choix qu'il est amené à faire lors des phases de conception. C'est pourquoi, dans notre thèse, nous nous sommes donc intéressés à développer une méthodologie qui va permettre aux entreprises de prendre des décisions fiables soient lors de la conception et le pilotage du système de production en identifiant et modélisant les phénomènes aléatoires (comme la demande, les pannes des machines) et en intégrant explicitement le délai de livraison dans le modèle. Ainsi, dans la première partie de notre travail, nous avons étudié un système de production constitué par une machine, un stock de capacité infinie et un client qui demande à chaque instant une quantité de produit. Nous avons appliqué à ce système un modèle à flux continus avec prise en compte d'un temps de livraison constant. Afin d'évaluer les performances de notre système, nous nous sommes basés sur la méthode d'analyse des perturbations infinitésimale (IPA) et nous avons réalisé des simulations à l'aide d'un algorithme basé sur cette méthode pour déterminer le niveau du stock optimal qui minimise la fonction de coût total. Ce coût total est la somme du coût de stockage, du coût de rupture et du coût de transport. Dans la deuxième partie de notre travail, nous avons appliqué, pour le même système que celui étudié dans la première partie, un modèle à flux discrets. La méthode d'analyse des perturbations infinitésimale (IPA) est également appliquée pour ce modèle pour déterminer le niveau de stock optimal. L'application de cette méthode à un modèle à flux discrets est une innovation. En effet, D'après nos connaissances, il n'existe pas des travaux qui appliquent la méthode IPA à des modèles à flux discrets. Dans la dernière partie de notre thèse, nous avons considéré un système de production avec un délai de livraison planifié entre le client et le producteur. Nous avons ensuite étudié l'impact des coûts de livraison sur le niveau de stock optimal. La méthode d'analyse des perturbations infinitésimale est également appliquée pour les deux types de modèles (modèles à flux continus et discrets) / The first part of our work, we study a manufacturing system composed of a machine, a buffer with infinite capacity and customer. We applied this to system a continuous flow model taking into account a constant delivery time. To evaluate the performance of our system, we relied on the method of infinitesimal perturbation analysis (IPA), we performed simulations using an algorithm based on this method to determine the optimal buffer level which minimizes the cost function. This total cost is the sum of inventory cost, backlog cost and transportation cost. In the second part of our work, we applied a discrete flow model to the same system studied in the first part. The infinitesimal perturbation analysis method (IPA) is also applied to this model to determine the optimal inventory level. Applying this method to a discrete flow model is an innovation. Indeed, as we know, there is no work applying the method to IPA models to discrete flow. In the last part, we considered a manufacturing system with a random delivery time between the costumer and the producer. Then we studied the impact of transportation costs on the optimal buffer level. The method of infinitesimal perturbation analysis is also applied for both types of models (discrete flows and continuous flows model).
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Modélisation des piles à combustible dans un environnement d'électronique de puissance / Fuel cells modelling for power electronic applicationKaewmanee, Wattana 08 March 2012 (has links)
Ce travail présente un modèle de pile à combustible plus approprié au domaine du génie électrique. Le modèle qui en résulte doit être en mesure d'intégrer des circuits électroniques de puissance et de donner des informations plus pertinentes que les modèles empiriques de type circuit. Les phénomènes du coeur de pile à combustible ont été étudiés. Les analogies entre mécanique des fluides et électricité ont été utilisés dans ce travail. Nous avons introduit le principe du flux d'énergie à notre modèle. Ceci garantit l'analogie appropriée entre deux différents domaines de l'ingénierie. L'exigence du faible coût de calcul exige de limiter le modèle à une seule dimension. Nous avons d'abord élaboré un modèle des tubes de gaz et des canaux pour les systèmes multi-espèces, puis, nous avons procédé à la modélisation des couches de diffusion de gaz, de la couche de réaction et de la membrane. A ce stade, nous avons obtenu un nouveau modèle de type circuit équivalent d'une monocellule de pile à combustible. Pour le modèle de pile n-cellule, la façon la plus simple qui peut être trouvé dans la plupart des ouvrages est de multiplier la tension de sortie d'une cellule par n. Toutefois, nous avons choisi de développer le modèle réel d'un stack comprenant 3 cellules, autrement dit, de modéliser 3 cellules indépendantes et donc de tenir compte de l'effet du canal commun de gaz qui assure la distribution de chacune des cellules d'un stack. Nous avons décidé de mettre en ?uvre le modèle sous Matlab / Simulink, logiciel très utilisé en génie électrique. Les résultats des simulations ont montré que le modèle fonctionne bien. Les phénomènes internes de la cellule sous conditions opératoires spécifiées ont été illustrés. La tension de sortie de cellule à partir du modèle est bien en accord avec les résultats expérimentaux. L'effet du réseau de canal entre chaque cellule de la pile a été exploré. Bien que le résultat escompté ait été obtenu, nous avons remarqué que l'effet du réseau de distribution de gaz, d'une cellule à l'autre d'un stack de 3 cellules était moindre. Ceci est dû aux paramètres géométriques du canal que nous avons implanté dans notre modèle qui correspondent à la structure réelle de la cellule, et qui est bien conçu. Néanmoins, cet effet devrait être fortement accentué dans le cas de stack comprenant de nombreuses cellules. Afin de vérifier que notre modèle atteint bien les objectifs visés, l'association d'un stack de 3 cellules et d'un convertisseur est simulée. Nous avons constaté que la simulation se fait sans difficulté et que le modèle autorise l'analyse de l'interaction entre la pile à combustible et le circuit convertisseur; l'objectif de la thèse est donc accompli / This work is an effort to create a more proper model for electrical engineers. The resultant model should be able to incorporate with power electronic circuits and give more insight information than the empirical circuit models. The mechanic of the fuel cell has been studied. The analogies of cell mechanics to electrical circuits were used in this work. We introduced the principle of energy port to our model. This guaranties the proper analogy between two different engineering domains. The requirement of the low computational cost suggested us to limit the model to only one dimension. We first developed a model of gas tubes and channels for multi-species systems, then, proceeded to the gas diffusion layers, the catalysts and the membrane. At this level we obtained a new equivalent circuit model of the single cell system. For the n-cell stack model, the simplest way which can be found in most literature is to multiply the single cell output voltage by n. However, we chose to develop the real 3-cell stack model, i.e., there was 3 independent cells in the system and the effect of common channels between each cell was incorporated. We decided to implement the model in Matlab/Simulink because it is common to most electrical engineers. The simulation results showed that the model is working weil. The internaI phenomena of the cell at the specified condition were illustrated. The cell output voltage from the model is weil agreed with the experimental result. The effect of the channel network between each cell in the stack had been explored. Although the expected result was obtained, we noticed that the channel network effect to the 3-cell stack operation was very small. This is because the channel parameters that we gave to the model are from the real cell structure, which is weil designed. Nevertheless, this effect should be more observable in a stack system which has higher cell number. To prove that the model can fulfill the ultimate thesis goal, the 3-cell stack model was connected to boost converter. We found that the simulation can be done without problem. The interaction between the fuel cell and the converter circuit is revealed; the objective of the thesis is accomplished
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A variabilidade climática e as mudanças de uso da terra: um estudo de caso da vazão e sedimentos da bacia do rio Piracicaba com modelagem numérica / The climate variability and land use changes: a case study of flow and sediments in the Piracicaba River basin with numerical modelingQueiroz, Mônica Rodrigues de 10 June 2014 (has links)
O objetivo desta tese foi avaliar os impactos decorrentes das mudanças de uso da terra e da variabilidade climática nos recursos hídricos (vazão e fluxo de sedimentos), em mesoescala (bacia do rio Piracicaba) e em pequena escala (microbacia do Ribeirão das Posses), através de um estudo de modelagem numérica com o modelo SWAT (Soil and Water Assessment Tool). Foram utilizados dados de modelo numérico de terreno, mapas de solo e uso da terra, temperatura, precipitação, vento, radiação solar e umidade relativa para forçar o modelo SWAT. O modelo mostrou resultados satisfatórios de desempenho na comparação com dados observados, conforme mostram os índices estatísticos na bacia do rio Piracicaba (COE entre 0,97 e 0,99 para vazão e de 0,90 para fluxo de sedimentos) e no Ribeirão das Posses (COE de 0,53 para a vazão e 0,7 para fluxo de sedimentos). Nas simulações de modificações de uso da terra os resultados indicam que em ambas as bacias as maiores vazões ocorrem nos cenários de desflorestamento, sendo o cenário de pastagem o de valores mais expressivos. O modelo correspondeu às evidências de que as vazões máximas, por exemplo os eventos de inundações, podem ser mitigados com o reflorestamento e que o cenário de antropização com gramíneas, no caso das pastagens e cana-de-açúcar, os eventos extremos tendem a ser aumentados ainda mais. Na avaliação da simulação dos fluxos de sedimentos, o cenário de reflorestamento por eucalipto mostra redução na perda do solo, porém ainda abaixo do cenário de reflorestamento por vegetação nativa, que apresentou os menores valores de fluxo de sedimentos, em ambas as bacias. Na simulação levando-se em consideração as mudanças climáticas, os resultados mostram aumento de vazão para o futuro (2078-2098) e consequente aumento de fluxo de sedimento, sendo um aumento médio de 12 % nas vazões do Piracicaba e de 19 % no fluxo de sedimentos. No Ribeirão das Posses este padrão de resposta também ocorreu, com aumento de 46% na vazão e 40 % no fluxo de sedimentos. / The aim of this thesis was to evaluate the impacts of changes in land use and climate variability on water resources (discharge and sediment fluxes), into mesoscale (Piracicaba River basin) and small-scale (watershed Ribeirão das Posses) processes throughout a study of numerical modeling with SWAT model (Soil and Water Assessment Tool). Data of numerical model of terrain, soil maps and land use, temperature, precipitation, wind speed, solar radiation and relative humidity forced the SWAT model. The model showed a satisfactory performance in comparison with the observed data, as showed by the statistical indices of the Piracicaba River Basin (COE between 0.97 and 0.99 to 0.90 for flow and sediment fluxes) and Ribeirão das Posses (COE of 0.53 to 0.7 for flow and sediment fluxes). In simulations of changes in land use the results indicate that in both basins larger flows occur in the case of deforestation scenarios, being the scene of the pasture the highest values. The model corresponded to the evidence that peak flows, for example the events of flooding can be mitigated with reforestation and the scenario of anthropogenic with grasses for grazing land and sugar cane, extreme events tend to be further enhanced too. In assessing the simulation of sediment flows, the scenario of reforestation with eucalyptus shows reduction in soil loss, but still below the scenario reforestation with native vegetation, which presented the lowest values of sediment flux in both basins. In the simulation taking into account climate change, the results show increased flow to the future (2078-2098) and consequent increase in stream sediment, with an average 12% increase in the flows of Piracicaba and 19 % in the flow sediment. In Ribeirão das Posses this response pattern also occurred with a 46% increase in throughput and 40 % in the stream sediments.
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Étude de la régulation de promoteurs inductibles par l’acide oléique chez la levure Yarrowia lipolytica dans un contexte de production de protéines recombinantesSassi, Hosni 14 September 2017 (has links) (PDF)
Les levures non conventionnelles, dont Yarrowia lipolytica, sont devenues desusines cellulaires attractives pour la production de protéines recombinantes. Lasélection de promoteurs régulés impliqués dans le métabolisme de substratshydrophobes est d'un grand intérêt pour une telle application. Dans ce cadre,l’objectif de ce projet est de mieux comprendre la régulation des promoteurs desgènes POX2 et LIP2 dans le but d’améliorer la production de protéinesrecombinantes chez Y. lipolytica.D’un point de vue biotechnologique, l'analyse à l’échelle cellulaire est devenueune approche répandue pour l’analyse et l’optimisation des bioprocédés. Ainsi,l'objectif de la première partie de ce projet vise le développement d’une méthoded’analyse en ligne des paramètres de culture Y. lipolytica dans un milieu contenantde l’acide oléique. Cette technique consiste au couplage d’un bioréacteur à uncytomètre en flux via une interface d’échantillonnage automatique. Cetteméthodologie a conduit principalement à une analyse rapide de la croissancecellulaire, de l'accumulation des lipides, du dimorphisme ainsi qu’à l'analyse duniveau d’induction des promoteurs chez Y. lipolytica.Les systèmes d’expression basés sur les promoteurs LIP2 et POX2 sont difficilesà manipuler, principalement en raison de l’utilisation de substrats insolubles dansl’eau (acide oléique) comme inducteur. Dans ce travail, il a été clairement démontréque pLIP2 est le promoteur de choix à utiliser pour développer un procédé deproduction de protéines recombinantes par culture de Y. lipolytica dans un milieucomplexe. De plus, l’utilisation d’un mélange acide oléique-glucose 60/40 (w/w) aconduit à une amélioration du niveau d’induction du promoteur LIP2 par un facteurde 10 par rapport à utilisation l'acide oléique. De plus, l’analyse à l’échelle cellulairemontre que ces deux substrats sont co-consommés par les cellules.Enfin, la dernière partie de cette thèse a eu pour but d'étudier la régulation dupromoteur LIP2 par rapport à la transition dimorphique. Nos résultats ont clairement montré que le changement morphologique chez Y. lipolytica n'a pas d'impact sur larégulation de pLIP2.L’ensemble de ces études a conduit à une meilleure compréhension de laphysiologie de Y. lipolytica, soulignant son potentiel avéré de production desprotéines recombinantes. / Doctorat en Sciences agronomiques et ingénierie biologique / info:eu-repo/semantics/nonPublished
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The Role of Stratosphere-Troposphere Planetary Wave Coupling in Driving Variability of the North Atlantic CirculationDunn-Sigouin, Etienne January 2018 (has links)
The wintertime North-Atlantic exhibits enhanced circulation variability relative to other areas of the globe and is a key determinant of weather and climate in the highly populated regions of Europe and Eastern North America. Previous work has linked extreme stratospheric polar vortex and planetary wave heat flux events with variability of the North-Atlantic circulation. To elucidate the role of the stratosphere in driving variability of the North-Atlantic circulation, the goal of this thesis is to clarify the relationship between extreme planetary wave heat flux and vortex events and understand the dynamical mechanisms driving extreme stratospheric planetary wave heat flux events using an idealized model.
The relationship between extreme stratospheric planetary wave heat flux and polar vortex events is clarified by comparing and contrasting their composite lifecycles using reanalysis data. Extreme negative heat flux events, defined as those less than the 5th percentile of the wintertime wave-1 distribution, involve stratospheric EP-flux divergence producing an acceleration of the vortex whereas extreme positive heat flux events, defined as those greater than the 95th percentile, involve stratospheric EP-flux convergence producing a deceleration of the vortex. Similar but smaller magnitude heat flux (22th and 78th percentile) events contribute to the development of longer-timescale vortex events. Negative heat flux events precede strong vortex events, showing that strong vortex events are true dynamical events involving wave-mean flow interaction. Conversely, positive heat flux events precede weak vortex events. The tropospheric jet shifts in the North-Atlantic that occur almost simultaneously with extreme stratospheric heat flux events are shown to be comparable if not larger than those that follow extreme vortex events for several weeks.
Next, a dry-dynamical core model is configured to capture the lifecycle of extreme positive and negative heat flux events seen in reanalysis. The events are not captured using the standard model setup with idealized wave-1 topography. A modified control simulation captures the key ingredients of the events: 1) the extremes of the stratospheric eddy heat flux distribution, 2) the cross-spectral correlation and phase between the stratosphere and troposphere, 3) the evolution of the eddy heat flux and EP-flux divergence, 4) the stratospheric evolution of the zonal-mean flow, including the NAM, NAM time-tendency, potential temperature time-tendency and stratospheric wave geometry, and 5) the tropospheric evolution, including the high-latitude wave-1 geopotential height pattern and mid-latitude jet shift. Comparison between the model and reanalysis reveals that higher-order planetary wavenumbers play a role prior to the events.
Finally, the dry-dynamical core model is used to examine the large-scale dynamical mechanisms driving extreme stratospheric negative heat flux events and their coupling with the tropospheric circulation. An ensemble spectral nudging methodology is used to isolate the role of: 1) the tropospheric wave-1 precursor, 2) the stratospheric zonal-mean flow and 3) the higher-order wavenumbers. The events are partially reproduced when nudging the wave-1 precursor and the zonal-mean flow whereas they are not reproduced when nudging either separately. In contrast, nudging the wave-1 precursor and the higher-order waves reproduces the events, including the evolution of the zonal-mean flow. Mechanism denial experiments show that the higher-order planetary wavenumbers drive the events by modifying the zonal-mean flow and through wave-wave interaction. Nudging all tropospheric wave precursors confirms they are the source of the stratospheric waves. Nudging all stratospheric waves reproduces the coupling with the tropospheric circulation. Taken together, the experiments show that extreme stratospheric negative heat flux events are consistent with downward wave coupling from the stratosphere to the troposphere.
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Atomic Layer Thermopile Film for Heat Flux Measurement in High Speed and High Temperature FlowsLakshya Bhatnagar (5930546) 03 January 2019 (has links)
This work seeks to apply the novel heat flux sensor called as the Atomic Layer Thermopile to measure high frequency heat flux in high speed and high temperature flows found in Gas Turbine combustors. To achieve this the sensor must be able to survive the harsh environment of high temperature and high pressure. To have any confidence in our measurement, it is also imperative that there are tools available for precise estimation of the measurement uncertainty. This works strives to achieve these objectives by developing calibration techniques for uncertainty estimation using both exposure to radiation and in convective environments by calibrating against power input in steady state flow and transient heat flux calculated using wall temperature measurement. The response of the sensor is then investigated in high speed flows by measuring the heat flux inside a supersonic nozzle when exposed to shock waves. The shock waves are generated using a fast throttle valve located at the entrance of the supersonic nozzle by generating sudden rise in pressure. Lastly a numerical study is carried out to design a cooling system that will allow the sensor to survive in high temperature conditions of 1000°C while the sensor film is maintained at 50°C. A one-dimensional model is used to provide initial design parameters and then a two-dimensional axisymmetric conjugate CFD analysis is carried out to obtain the desired geometry that can meet the design conditions. A static structural analysis is also carried out on this geometry to ensure that it will be able to survive and avoid distortion under the operational pressure required for providing the desired coolant mass flow.
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Detecção de Redes de Serviço de Fluxo Rápido Baseada em Otimização por Colônia de FormigaBarbosa, Kaio Rafael de, 981278437 04 April 2018 (has links)
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Previous issue date: 2018-04-04 / FAPEAM - Fundação de Amparo à Pesquisa do Estado do Amazonas / Remote control and remote access of malicious code-enabled computers allow the network operator (botnet) to perform various fraudulent activities such as orchestrating distributed denial of service (DDoS) attacks or propagating malicious code such as virus and IT worms. To maintain control of these infected machines, it is necessary to use a robust communication mechanism against attempts to disrupt network services and to be able to evade intrusion detection systems. Such a mechanism is also known as Command and Control (C&C) channel. To do this, some malicious networks often adopt the Domain Name System (DNS) because of its global and distributed operation, allowing them to simulate legitimate network behaviors from techniques such as Round-Robin DNS (RRDNS) and Content Distribution Networks (CDN). Malicious networks that employ these strategies are called Fast Flow Service Networks, because they are able to modify their behavior to ensure the continuous operation of the services, as well as the Command and Control (C&C) channel. To identify such networks, current intrusion detection systems are constructed from models based on a fixed set of attributes observed at a given time point. However, the operators of these networks are able to subvert such detection models by modifying characteristics such as the number of IP addresses or the lifetime (TTL) of a domain name. For these reasons, this work presents a bioinspired model in the concept of Optimization by Colony of Ants for detection of botnets based on Fast Flow Service Networks. The main objective is to analyze a suspicious domain from different perspectives, because even if it is possible to manipulate certain features, the operator is unlikely to modify a of attributes to evade different classification models at the same time. The experimental results using a real database show that the model is able to generate classification rules that prioritize lower cost from the combination of different detection methods, obtaining an accuracy of more than 93%. / O controle e o acesso remoto de computadores infectados por códigos maliciosos permitem ao operador desse tipo de rede (botnet) realizar diferentes atividades fraudulentas como orquestrar ataques distribuídos de negação de serviço (DDoS) ou propagar códigos maliciosos como vírus e worms. Para manter o controle dessas máquinas infectadas, é necessário utilizar um mecanismo de comunicação robusto contra tentativas de interrupção dos serviços da rede e que seja capaz de evadir sistemas de detecção de intrusos. Tal mecanismo é também conhecido como canal de Comando e Controle (C&C). Para isso, algumas redes maliciosas adotam com frequência o Sistema de Nomes de Domínios (DNS) devido ao seu funcionamento global e distribuído, permitindo assim que simulem comportamentos de redes legítimas a partir de técnicas como Round-Robin DNS (RRDNS) e Redes de Distribuição de Conteúdo (CDN). Redes maliciosas que empregam essas estratégias são denominadas como Redes de Serviço de Fluxo Rápido, pois são capazes de modificar seu comportamento para garantir a operação contínua dos serviços, assim como do canal de Comando e Controle (C&C). Para identificar essas redes, os sistemas de detecção de intrusos atuais são construídos a partir de modelos baseados em um conjunto fixo de atributos observados em determinado instante de tempo. No entanto, os operadores dessas redes são capazes de subverter tais modelos de detecção pela modificação de características como a quantidade de endereços IP ou tempo de vida (TTL) de um nome de domínio. Por esses motivos, este trabalho apresenta um modelo bioinspirado no conceito de Otimização por Colônia de Formigas para detecção de botnets baseadas em Redes de Serviço de Fluxo Rápido. O principal objetivo é analisar um domínio suspeito a partir de diferentes perspectivas, pois mesmo que seja possível a manipulação de determinadas características, é improvável que o operador modifique um conjunto considerável de atributos para evadir diferentes modelos de classificação ao mesmo tempo. Os resultados experimentais usando uma base de dados real mostram que o modelo é capaz de gerar regras de classificação que priorizam menor custo a partir da combinação de diferentes métodos de detecção, obtendo uma acurácia superior a 93%.
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Numerical investigation of a plunging airfoilJanechek, Matthew James 01 July 2017 (has links)
This thesis investigates vortex dynamics of a plunging airfoil by studying the vorticity transport mechanisms of two-dimensional direct numerical simulations. The simulations were used to study a simplified flat airfoil in a freestream that was subject to pure plunging motion. Quantitative and qualitative analyses were used the validate the two-dimensional simulations and gain insight into the effects of eliminating three-dimensional physics in a nominally two-dimensional flow. Additionally, a parametric study was conducted to analyze the effects of Reynolds and Strouhal numbers on the transport of vorticity.
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[pt] CARACTERIZAÇÃO DOS FLUXOS HÍDRICOS EM TRÊS ESTÁGIOS SUCESSIONAIS NA SUB-BACIA DO RIO CAÇAMBE, MACIÇO DA PEDRA BRANCA (RJ) / [en] GROSS RAINFALL AND THROUGHFALL IN THREE SECONDARY SUCCESSION GRADIENTS OF ATLANTIC RAIN FOREST ON CAÇAMBE SUB-BASIN, PEDRA BRANCA MASSIF (RJ)HENRIQUE FURSTENAU TOGASHI 15 March 2011 (has links)
[pt] São avaliadas a precipitação e seu fracionamento em três estágios de sucessão vegetal em estudo na sub-bacia do Caçambe, maciço da Pedra branca, Rio de Janeiro. No período de 04/11/2010 a 04/11/2011 foram realizadas 27 coletas após os eventos de chuva. Utilizaram-se 12 pluviômetros em uma área de floresta secundária avançada, 6 em uma floresta secundária inicial e 6 na borda entre as outras duas tipologias. A precipitação da série foi 2357,07 mm. Os fluxos de atravessamento, 89±13% na borda, 94±14% na tipologia inicial e 75±07% na tipologia avançada, estão de acordo com valores médios para a Floresta Atlântica. Os resultados indicam aumento de interceptação com o avanço do estágio sucessional, o que sugere a importância da preservação florestal para garantir interceptação mais eficiente da água da chuva, em especial em uma cidade sujeita a alagamentos como o Rio de Janeiro. Das 27 coletas, analisaram-se os elementos Na+, K+, Mg+2 e Ca+2 em 12 coletas. Os resultados assemelharam-se com a literatura, à exceção do Ca+2, com valores altos para concentração e para fluxos. Os resultados indicam que a expansão urbano-industrial na zona oeste da cidade pode estar contribuindo com um quadro de fragilização ambiental, pelo excesso de emissões de metais e pela capacidade de interceptação reduzida com a retirada de cobertura vegetal. Acredita-se que esta fragilização pode ser potencializada pelos registros do Rio Centro de tendência decenal de aumento de chuvas, e em especial da intensidade entre dezembro e abril, período de maior ocorrência de movimentos de massa e alagamentos. / [en] It is presented results from observations of gross rainfall and throughfall regimes for three successional phases in a stand located at Caçambe sub-basin, Pedra Branca massif, Rio de Janeiro. From 04/11/10 to 04/11/11 were carried 27 samplings after the rain events. Gross rainfall and throughfall were measured with 12 rain gauges in an area of advanced secondary forest, 6 in an early secondary succession and 6 in the edge. Total gross rainfall was 2357,07 mm. Average throughfall, 89±13% in the edge, 94±14% in initial secondary bush and 75±07% in advanced secondary forest, are in range of literature values for the Atlantic Rain Forest. Interception increased simultaneously to the advance of the secondary succession. This improved interception suggests the importance of forest preservation to mitigate flooding in vulnerable cities such as Rio de Janeiro. Chemical analysis for Na+, K+, Mg+2 e Ca+2 were evaluated in 12 out of 27 rain events. The results resembled literature, with the exception of high total quantity and concentration to Ca+2. The urban-industrial expansion in the zone west of the city is spoiling the forest patch and probably is causing the excess of metal emissions at Caçambe. In addition, Rio Centro record confirms a growing gross rainfall tendency in the end of this decade. From December to April is the mass movement and flooding period in Rio de Janeiro and its increasing intensity of gross rainfall completes the environmental fragility scenario.
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Comparison of Agricultural Area Source Ammonia Gas Concentration and Flux MeasurementsReese, Emyrei 01 May 2010 (has links)
This study was conducted in order to compare and evaluate a variety of ammonia (NH3) measurement techniques for determination of ambient gas phase concentration and evaluation of system fluxes. This was accomplished by measuring NH3 emitted from area sources within two dairies, one located in south-central Idaho and another in central California. The measurement techniques utilized included: an array of passive diffusion samplers, a single annular denuder system, a single or paired Fourier transform infrared spectrometer(s) (FTIR), a paired (upwind and downwind) set of differential optical absorption spectrometers (DOAS), and a portable wind tunnel in conjunction with a chemiluminescence monitor. The concentrations measured were manipulated by methods of inverse modeling using the ISCST3, AERMOD, and WindTrax models to yield estimated emission rates for individual sources, as well as an overall dairy emission rate. Furthermore, a comparison of the different techniques took place, and it was concluded that in the context of measuring agricultural area sources, the spectroscopy techniques, FTIR and DOAS, were likely the most desirable systems. This conclusion was based on the systems' ability to yield high precision, path integrated concentration measurements that do not require actual collection of sample. However, as long as a proper deployment scheme is utilized, the passive diffusion samplers also offered a viable option, especially when funding is limited.
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